he need 16 minutes which i can tell you in 1 comment: yes, he have a greater consumption if he accelerates more, BUT he need more time. time is money, not fuel. drive efficient and not as slow as you can. everyone have less time in their life as they think!
One thing to consider that is harder to test as rigidly as done with this video: When I accelerate hard(er) I reach my cruise speed faster than accelerating softly, that means I can go for a slower cruise speed while keeping the same average speed as the softer acceleration. Combining that with the high-throttle, early shifting approach, which gave a good balance between economy and accleration in your test, might still be the way to go.
I find this depends a lot on what engine and how harsher we're talking about. For example my car wether I accelerate gently you can just watch the instantaneous consumption and it's the same as a moderately hard acceleration. Meaning accelerating moderately hard would actually save fuel compared to being gentle as the acceleration phase would use the same liters/100km while being shorter, however if I overdo the harsh acceleration it obviously ruins the economy. However I've driven cars where as soon as you even touch the accelerator with some intent the consumption goes crazy meaning that technique definitely wouldn't work. Now that I think of it most of the cars I've driven that are like mine and can be accelerated a bit harder while not guzzling more gas were diesels, and the ones that would use a bunch at any hit of the throttle were gas so it's probably related.
This will be because the journey times (and therefore) average speeds are different. Air resistance is proportional to velocity squared. Regardless of acceleration lower speeds will improve fuel economy.
With turbo and manual u can accelerate a bit harder than normal use same or less fuel. But usually we change at 2000rpm or lower if condition allowed. And obd2 reading confirm my car is most efficient with gentle acceleration. My car is 1 liter manual Fwd. And can do 25km per liter.
My car has a powertrain issue or a blockage somewhere like the exhaust because it has to be driven at >2-3k rpm if you go under this the car has major power loss and pulling away from junctions you have to almost slip the clutch to pull away sometimes. Very frustrating to drive.
The distance travelled should have been further, 1 full mile or so, since the whole point of quicker acceleration is to get up to speed so it averages out over the long run.
Engines are most efficient at WOT and peak power. If they weren't then your cylinder deactivation would be for full throttle rather than cruising at highway speed.
Great test! As a hardcore hypermiler, I love to see these fuel efficiency testing videos. What I found is that how you accelerate matters much less than what you do after you accelerate, but I have gotten my best tanks by a small margin accelerating at a moderate rate and shifting at around 2000-2500 RPM. At least on gas engines, efficiency tends to be best at a medium-low RPM and a medium-high load. If you would like to see a visual example of this, look at some BSFC charts. Too little load and/or too much RPM and pumping losses and frictional losses make the engine less efficient; too much load and the ECU commands a rich air/fuel ratio and the engine becomes less efficient because unburned fuel is wasted out the exhaust. How you slow down matters much more. Remember that every time you press the brake pedal, you are basically turning your expensive fuel into brake dust and heat. Letting off the gas really early for stop signs, red lights, turns, etc, and leaving a lot of distance in front of you in traffic so very little or preferably no braking is required is where most drivers will see their biggest gains without getting into drastic car mods or more extreme driving techniques like pulse and glide or engine off coasting.
The BSFC varies between engine types, engines with forced induction tend to perform best at lower rpms compared to naturally aspirated ones, and the same goes with 2 valve per cylider cars vs 4 valve. But general rule of thumb (BSFC charts for every engine are hard to come by) is to use RPMs close to peak torque (eg. peak torque is at 3000 so you should use 2500-3500rpm) under generous throttle (but not with pedal to the metal), and as always go straight to highest possible gear when done accelerating. Hypermiling is one of my favourite activities on long trips, but what you said is 100% true - the worst thing that you can do is braking. I'm able to go between 100-150 kilometers without using the brake pedal just by observing the road before me and acting accordingly. There is also the factor of gravity and potential energy, pulse and glide is not the best technique when being in normal traffic, but can do wonders when used correctly on a road with a lot of uphill/downhill combinations.
@@jakubm1187Great points. I wish BSFC charts were published by manufacturers, it would sure make life easier for us hypermilers. I wonder how true the theory that maximum efficiency occurs at peak torque RPM is on higher revving engines. Both of my cars make peak torque at around 5K RPM, but I can't imagine that shifting so late could be most efficient way to accelerate. As for pulse and glide, it certainly has its place. I have found it to be very effective on hilly roads (obviously not on hills so steep you will pick up too much speed on the way down). I have heard of good results using pulse and glide on longer highway trips instead of maintaining a constant speed, which makes sense especially if the top gear is short. With a tall geared transmission that has the engine cruising at barely above idle anyways, I'm sure pulse and glide wouldn't be as beneficial as with shorter gearing since frictional losses and pumping losses would be less anyways.
Interesting. I'm not exactly hypermiling right now (115 kph on highway, 70 average) but for now I can reach huge distances with driving relatively quick that driving behind me becomes no burden. I usually shift at 2200 RPM which is pretty much the middle of what you stated. My 13 year old Ford Mondeo TDCI on average can manage 1300km (or over 800 miles) if I keep doing this.
When you accelerate very gently, you are spending more of the time at a lower speed and therefore reducing aerodynamic drag losses. Even though you hit the same top speed of 50mph, your average speed is lower with the gentle acceleration. I would like to see a test with different acceleration rates where you stop accelerating at the speed where the car gets its best gas mileage.
Compared to in-engine losses, drag doesn't become a problem until about 50-55mph. V^2 and all that. You'd notice it comparing cruise speeds over long distances, but not in this case.
Apart from this test mixing two variable changes together (throttle position & RPM at which he shifts), the true comparison would be which combination of acceleration and top speed gets you to the goal in the same time (ie, faster acceleration would be combined with a slightly lower top speed).
according to the law of conservation of momentum (force = mass * acceleration) the car's mass remains constant, while the acceleration changes. this means that force is directly proportional to the acceleration. having a larger acceleration will require a greater force, which in turn uses more fuel for the acceleration.
@@totallynotkacper7629 Yeh, but your total momentum change in both cases is identical. As is the total added kinetic energy. The answer lies in the engineering, not the kinematics.
@@totallynotkacper7629 faster acceleration requires a greater force for the duration of the acceleration, but that duration is smaller compared to a slower acceleration, so it should cancel each other out
My mother and grandfather both have near-identical cars (same engine, same mileage - 170k), and they both drive similar roads, and yet my grandfather gets about 20% more MPG than my mother. For years I've been saying it's because she's the type of driver to get to the speed limit as fast as possible, then brake at the last possible minute, whereas my grandfather drives 'properly'. Her reason for that driving style is that she was taught to drive right next to the motorway, and we have a load of country roads where you really have to accelerate when you pull out of a junction. I can kinda see that being a valid reason, but there's no need to drive like that everywhere!
I sold my father in law's car. I drove it myself for a week. 1.4 na engine. Checked the BC when I collected it, drove some 500 miles. Result: 72% better mileage.
@@shadmansudipto7287 Yeh, I've observed that. I've also observed octogenarians who are as sharp as they come. A lot of it will come down to how much use that brain sees, and I plan to keep mine as active as I can
I hate it when people stop abruptly past the stop sign or start to speed up before I can even pass the sign. You never know if they are actually going to stop in time & I'm always ready to swerve away from the vehicle if they don't stop but that's not always an option with oncoming traffic.
If the constant speed phase is much larger than the video, the difference becomes negligible, it seems. Since we have a short run on the video, it becomes more pronounced. This was a great video, answering a question that I had myself. Now I know that, at least in urban driving, there's absolutely no reason to get "spirited" while driving, since the constant speed phases are very short, and acceleration/deceleration takes much of the total runtime. On a highway I'll be pleased to accelerate faster to merge, knowing that it won't hurt my MPGs that much.
@@tommik4872 Exactly. As this video shows, the way you accelerate just isn't all that critical when it comes to overall fuel efficiency. If he accelerated then cruised for 10 miles, any differences in efficiency as a result of how he accelerated would never be seen due to normal run to run variance and wouldn't be as conclusive. The way he did this test was perfect IMO since he needed to keep all the tests the same distance while still leaving enough room for the very slow acceleration test.
I drive in bumper to bumper traffic in my 1.5 tsi engine and get a fuel economy of 6-7 kmpl when using fast accelerations and 8-9 kmpl when gently accelerating and braking (over 15-20 kms), so yeah, the difference isnt negligible in bad traffic/ roads
I think the big reason for your results is the turbocharge. Most turbocharges have peak torque earlier, in the 1500~2000 range, which means you get more work and power delivered earlier. In an aspirated engine, peak torque is usually reached over the 5000 RPM limit.
Exactly what I have been debating so far. Why are you always in my head? Jokes aside, thanks for the video! You've been a great resource for my manual transmission journey here in the US.
Great experiment, and I was happy to see the theory play out in practice that low RPM and high load results in good economy. One of the things that irks me about cars with automatic transmissions but without electronic throttle control is that you can't really drive them this way: when you open the throttle it will also prefer a lower gear because it thinks you want more power. Still, I do like the way the CVT in my car generally allows decent acceleration to urban road speeds without the engine speed rising above 1500 RPM.
@@daniel27560 Haha, fair question! My friend was selling it and it was extremely cheap. :) TBH, I remember being curious about CVT drivetrains in high school, purely from a technical perspective, but I'd be the first to admit that they're not very exciting to drive.
Fantastic adherence to methodology and I love that you worked so hard to control as many variables as you could! I do fear one thing may have been overlooked though: built-in fuel efficiency indicators on vehicles are notoriously inaccurate from vehicle to vehicle - especially over extremely short durations. They rely on pre-ordained formulas built into the ECU logic based on RPM, requested torque which is a fudged guess from the ECU anyways, fuel pressure or manifold pressure, and - this is the kicker: throttle position. While they may work better over long trip durations (error averages out) and certain vehicles may be more accurate than others (Nissan & Hyundai are notoriously bad, whilst Subaru and Mazda seem to be slightly better), you'd be better off testing this either with longer test cycles and direct measurement of fuel before and after, or in a lab. Still, subscribed. I love your dedication to clear and succinct presentation of info!
Yeah, was gonna say similar. I thought he had some sophisticated fuel-dripping rig set up, but instead relying on the car's own built-in computer, which is constantly estimating the future as much as the past. As such it's just spitting out pre-written data. On the bright side, this is data directly from the car maker, on the downside, car makers lie about their product's mileage all the time, so... *shrug It's good to see the actual testing anyway, as there's no reason for the makers to lie about which method works best for fuel economy. I suspect the whole issue is more about weak engines pushed hard, rather than a strong engine working gently, as it's obvious a strong engine will use less fuel when it's not working so hard. My own experience with economy crap-boxes is they use as much fuel as a better car, cos I have to hammer the things much harder to drive like a normal human.
@@bigglyguy8429 the only real truth is going to the pump and seeing how many miles covered. (Although is this this really the truth? You need the same fuel click off point in each pump. Also, just like your speedometer reads a slightly higher speed, does your odometer read slightly shorter miles? I don't know.)
@@TimpBizkit Well I know for the fun of it I've been driving my stage-4 tuned Hilux Vigo turbodiesel off-road beast of a machine more gently... and people keep driving around me and seem to think they're winning a race! Normally I just drive away from traffic. I didn't realize people were so weird..
I was wondering how accurate the fuel consumption figures were at different RPM points. If the fuel consumption figure underreads at lower revs then the results will be skewed towards low acceleration giving the best results. Without knowing how the fuel consumption is worked out this may or may not be a good experiment. I read a news item in the past month that a couple of different sets of experiments found that accelerating at about 66% of maximum acceleration was the best way (wrt lower fuel consumption) to get up to speed quickly and into top gear. This is an example of the usual mixed messaging that can be found on the internet, same question two different answers.
Yeah, there's no way that thing was good enough to do a test like this. There are so many things that could be causing it to report better efficiency when he accelerates slower, and worse efficiency when faster, and in reality it could be the opposite
Very interesting findings, gentle is the way to go, but not very fun :P I really do wonder how a diesel would fare here. Not sure if this particular engine does it, but some (maybe they all do it, not sure?) turbo petrols at high loads (full throttle) and low rpm tend to run rich to prevent knock. No such thing in a diesel, since it can basically run on fumes without worrying about knock and air/fuel ratios, so I wonder if there would be more of a benefit of hard acceleration (70-80% throttle seems to be the general rule of thumb on some TDI forums i've read) and shifting at let's say 3000 or wherever the peak torque ends and not redline at 4500.
@@ConquerDriving yeah disel works great at 5-6th gear about 2k rpm u can get about 4.5 L/100km with 1.6 enengine but lower speeds take a lot off fuel at city driving,specially with higher rpm
Love the video. I would bet that the reason Full throttle and half throttle were that high was because you stayed in 1st for so long. 1st destroys your mileage. In my own tests, the best option between speed/mileage was 1st until 2k then 2nd to 35mph. The goal with 1st was to get into "Turbo range" for second. Also no need to full throttle 1st, it's wasteful. All in all, your results match my experience. Cheers for the dope channel, your manual control is top notch.
The theoretical numbers behind engine efficiency is in BSFC (Brake Specific Fuel Consumption). It's basically a 3D plot of engine RPM (X-axis) vs throttle position or torque (Y-axis), and on the "Z-axis" is the amount of fuel needed to generate a certain amount of energy (kWh or MJ). Less fuel is obviously better. For many engines, this is somewhere within the peak torque band at a decent -but not quite full- throttle load. Now I don't think many people would use "exactly 80%" throttle to get their best fuel economy, so it's not really realistic way of driving (unless manufacturers would make 80% the new 100% lol). But it is entirely true that petrol/diesel engines only get "more efficient" at higher speeds. The better fuel economy is just in the speed and losses involved..
A lot of manufacturers actually put an efficiency ‘bump’ in their accelerator pedals nowadays where it feels like it stops at about 80%, but you can push past it to 100%. Not sure if it’s a Renault/Nissan thing but my work van has it & it seems like a really good idea.
No exaggeration, you are actually doing the nation a service with these videos 👍😂. Teaching people (for FREE!) on how to save money in times like this! Proper quality contentas always👌
I love you for putting the results in all different units. I always hate it when I have to open a new tab mid video just to keep track of the mpg -> L/100km ratio
Fuel burned accelerating is justified, but economy in my opinion comes from stopping. When you accelerate you convert liquid dinosaurs into kinetic energy, so economy depends on how you use that kinetic energy. While stopping you can let it dissipate in justified air, rolling, engine resistance and so on, or your dissipate it in your brakes.. I would like to see the test where you reset computer at 50 mph, drive for a while and make an emergency stop at defined spot. Then try resetting, coasting to 20 mph then apply brakes to stop at the same spot. And third run try downshifting and braking with engine till 20 mph and then apply brakes. Most efficient will be downshifting. This driving style could be harder to master in real life conditions, but I get manufacturers claimed range on all cars I ever have driven. Thanks for the great video! 👍👍
The one where you accelerated briskly to 3,000 RPM seems to be the best of both worlds. Economy was decent, and you may be able to merge onto a highway if the slip road is one of the longer ones. But, as said in the comments, it doesn't make that big of a difference in the big picture, so obviously safety over fuel economy, and a bit more progress as a bonus.
The run where he floored it and changed gears early, I think he got hood mileage because you spend a decent bit of that time in neutral shifting 5 times. Regardless it’s not healthy for the engine to be flooring it under 2k, especially turbo charged ones. Mine throws misfire codes the moment I get into boost under 4k if not fully heated lol.
I think for the slowing down part, the efficiency not comes with decelerating slowly, instead cutting throttle early. As long as you let the throttle off, it should change a lot if you're slowing down quickly or not. Lift and coast is the key.
Given how close the results are between normal and hard acceleration on a turbo engine I feel like an NA engine might actually do notably better as a result of not needing nearly as rich an AFR for cooling.
@@marvin2678 depends on your definition of properly. IMO fuel economy is the least important thing to cater your driving style to. I would drive either engine mostly the same. Don't rev too high while the engine is cold. Once it reaches operating temperature, you should not be afraid of getting near the redline on acceleration. This does not hurt the engine and in fact helps keep it clean. Modern manual cars will tell you to upshift too much, too soon, for fuel economy and emissions reasons. Automatics just plain force this on you. But this can get you into lugging the engine and bad throttle response situations. Don't hesite to downshift when you expect to load the engine soon, even just a bit. It'll greatly increase the general feeling of driveability of the vehicle. Both turbo and non-turbo engines have an operating RPM from which upwards they will start to feel responsive. This is where you want to be when you start to accelerate or climb a hill. Only lower engine RPM by upshifting AFTER you reach low load and constant cruising speed. This point will vary from engine to engine, turbo or no turbo. Try to find this point for yourself by accelerating in, say, 3rd gear from low speed to redline. Somewhere along they way, like maybe 2000 RPM for example, the engine will start to feel and sound "happy". The only real difference in feel between turbo and non turbo engines is how and when the engine transitions from unhappy to happy. Getting back to fuel consumption tho, the turbo engine will use more fuel in the happy area, despite being physically smaller than a non-turbo engine with the same horsepower output because it uses extra fuel for cooling of the combustion mixture. The non-turbo engine will use more fuel in the unhappy area because it has more internal friction. I have a personal preference for the latter because I drive a lot in the happy area. Non-turbo engines also just feel and sound better to me.
The run where you changed up late but didn't accelerate hard sounds to me pretty similar to people who just won't press the gas pedal more than a certain amount, so going up hills they stay in low gears for a really long time because they don't want to give it more throttle to get up to speed.
I think the idea behind smooth acceleration is most important in cities when you're starting and stopping a lot. Going from 50 to 0 burns twice as much fuel as going from 25 to 0. Going slower overall rather than going right to the limit every time you move saves fuel, you're just going to waste it all anyway when you hit the brakes and turn that precious energy into heat.
Actually, going from 0 to 50 is significantly more energy usage than 0 to 25. In fact, it's at least 75% more, even if there wasn't drag or friction involved.
As others have mentioned, a lot of turbocharged engines need a rich air-fuel mixture when the engine is under boost to keep detonation at bay. At the same time, I have my reserves trying the high throttle, low RPM shift on a turbocharged engine, given the risk of low-speed pre-ignition(LSPI). One info that would be nice to see is the intake manifold absolute pressure(IMAP), or more simply, just how much boost/vacuum the engine is under. Half throttle might be okay for a layman's understanding, but for more technical folks that know every car has different throttle mapping nowadays(sometimes changing the driving mode will change the mapping within the same car), it's a bit too general. Is half throttle putting the engine in lighter boost, no boost/vacuum(almost simulating full throttle in a comparable NA engine of the same displacement), or a slight vacuum? People with an OBD scan gauge can use this info to their advantage. Then there is the elephant in the room: you are reading the estimate in the gauge cluster. Now I understand that it's unrealistic to fill up after every run and longer drives would introduce more variables to throw the test off, but realize those things are sometimes pretty wonky. The one in my Camaro for example can be anywhere between -2%~12% better compared to the actual fuel efficiency(using miles driven and fuel filled up from the receipt). It tends to be 10% better than the estimate but that's not always the case. Mazda ones are typically a bit more trustworthy in my experience, but those also sometimes show worse efficiency in the gauge cluster than the actual mileage. Oh well, I don't really drive for economy myself for the most part. My fun car with a stick shift is a V8 so I drive for smiles per gallon, and my other beater is an old automatic. I do somewhat aim for slightly better economy for it but other times, I let my silly side take over and let VTEC kick in, yo.
AEM sells a great AFR and boost gauge (failsafe) and I have one on my turbocharged car. I think it would be most efficient to give it about 70% throttle and change at 2500-3500 RPM depending on your car while being smooth with the throttle movements, making sure not to lug your engine or run rich AFR. I could do this but my car's MPG readout updates quite slowly and it would be hard. I haven't tested with this car but my previous car's MPG estimate was spot on, albeit with slightly larger tires than stock. V8 honda? 1st gen NSX?
"smiles per gallon" is exactly how I drive my car on a twisty B road in England. Its only a 148bhp Focus but its fun when let loose. Who cares about economy when youre having fun!
@@CrazyInWeston I wish there were fun roads near me, there's a road with 1 good and 1 decent corner near me. Little elevation change = few curves. I love Texas but I have not found any fun roads that I can safely/legally go fast enough to have fun on.
@@johnhunter7244 Prob why on the worlds "greatest driving roads" Jeremy Clarkson said it wont be in the USA because "everybody does 5mph" he also saw said it wont be Australia because "its full of Spiders" and not Africa "because everyone rides an ox" or the Middle east cos "the Americans will shoot you"
The instrument cluster reading is generally quite accurate. Its accuracy is by product of the ECU needing to very precisely meter fuel into the engine to ensure target AFR and emissions compliance.
If you try this same experiment with a very efficient Electric Vehicle it might actually be more efficient the faster you accelerate as long as you take the same amount of time to cover the same distance. Work done accelerating varies with the square of change in speed. If you accelerate quickly you don’t have to reach the same top speed to have the same average speed.
@@ConquerDriving I would like to see the difference too. My brother and I both have Ford Fiestas with direct injection and 5 speed manuals and 15 inch wheels. Mine has the turbo 3 cylinder but my brother has the NA 4 cylinder. He has far less torque down low so his gears are far shorter than mine. My economy should be better during acceleration as I can keep my engine speed lower but on the highway economy is almost the same even though his cruising rpm is higher. Would be interesting to see just how much turbo vs NA engines vary across a range of engine and driving speeds.
Actually a further distinction needs to be made: a small turbo does indeed increase torque at low RPM, whereas at high RPM it has to open the waste gates (which removes much of the efficiency benefit). So this favours a low-RPM driving style. At high RPM it's hardly different from an NA engine - in fact rather less efficient, because the engine itself will generally use a lower compression ratio. By contrast, a large turbo doesn't even spool up at low RPM, which ruins both torque and efficiency. This is one reason powerfully turbocharged sports cars can't be efficient even when driven at low speed. However, a small engine with comparatively big turbo can actually be quite efficient, even at high RPM - while being completely useless at low RPM.
Interesting test, but I think a naturally aspirated car would be a better candidate for this test, in my experience their economy is more linear than a turbo car. In my case, my Evo X GUZZLES more fuel under boost, far far more than cruising below 3K RPMs. I commute the same trip daily for years, so I have tried many things to get better gas mileage, the best way for me, is to drive like an old lady, shift early, keep speed as low as possible, with around 40 MPH, 65 KPH, being the sweet spot for fuel economy. My best efficiency was when I accidentally forgot to put the oil cap back on and the engine wasn’t getting boost 😆, it was like, wow, 37 MPG, I’ve never seen it that high before
Very interesting video, makes me want to do my own tests. One thing to note here is that you are changing gears at different RPM's for each throttle level. Doing tests where you shift up at the same RPM, while changing the throttle amount may show different results. In order to complete it you could even do the same for other RPM levels. That being said, on its own it is already interesting to see the difference between an aggressive driving style (more throttle, shifting later) and a relaxed driving style (less throttle, shifting earlier) is already a good real world test
1. In all cases, you need to burn the chemical energy required to reach the kinetic energy level of your intended cruise speed. Right off the start, it doesn't matter much if you derate 2. If you derate from peak power to peak efficieny, you will save some gas as the friction losses inside the engine are lower for a few seconds. You will often be a nuissence to traffic though. 3. Your average speed may decrease, but then it's more efficient to reach the same avergage speed with a lower cruise setting and a quick acceleration. That said, in order to drive fuel efficient: - lower your cruise speed (especially on roads where it is easy to pass) - don't use the friction brakes, retain as much kinetic energy as possible when maneuvering (- don't open the windows as it will induce drag) (- turn off unneccessary subsystems in your car) (- don't load stuff in your car you don't need) (- turn off the engine when you don't need it) If you want to modify stuff: - go for energy efficient tires (you have a conflict of goals as these offer less traction) - inflate your tires to the high end - use low viscosity motor oil, but it has to be approved by the car manufacturer for your climate If you buy a car, go for a long one if you need space. The more surface area you put against the wind, the more your fuel burn will be.
Something that genuinely works especially on older cars is to drive very conservatively on a daily basis with an occasional thrash to help clean out the engines carbon. My old VR5 bora was averaging 28mpg and after a 4 hour hard thrash on a day out with a convoy group (with a double shot of engine cleaner) I was then averaging 34mpg.
Sorry, but highway/motorway(?) is not more efficient due to increased load. Its the increased consistqncy of speed (less stopping/starting | slowing/accelerating) that allows a motor to stay more so in an efficient range therefore reducing the amount of time under increased load. You said it yourself, that car is most efficient around 30/45. But you're probably spending less time at that speed on the highway/motorway(?) than city/rural roads. Hence why city driving typically is rated as lower despite being at a more efficient speed [sorry, but all petrol / diesel engines (atkinson cycle* and 2 stroke (still considered atkinson cycle?) ) waste lots of energy on making heat and noise. They're very thermally inefficient (something like a turbine produces more power and less thermal waste) ]
The tests, the explanation, the info for us and eu drivers, the camera's... this gotta be the most complete youtube video I've seen in a good while. Thanks!
good comparisment but half of us cant use this information since older cars dont have electronicly controlled gas pedals like you have.... "older" cars (like ~2006 and earlier) have bowden cables and very little to no electric fuel control (which mostly is not really a bad thing...) BUT the results will be fairly different from yours... also cars with no direct injection act differently than yours even with fuel ECU's... (also cars with an caburator, completely different but i guess they're mostly dead anyways.. :/ )
Passed my test first time today! Just wanted to say a massive thanks Richard, your videos have helped so much during my learner driver journey and they would make concepts so much more easier to understand when watching before lessons and leading up to the test day. Keep up the brilliant work and all your effort in videos is very much appreciated :)
I drive a 16 plate octavia 1.4 150 estate. I’m that driver that sometimes uses 3/4 to full throttle but shifts really early. 1.8-2k rpm. I average 44mpg on the edge of London. When I relax I can sometimes get 60mpg.
BMW did a study some (15?) years ago. Full throttle, but all shifts at 2,000rpm. Lowers pumping losses. Works well on my Cooper S, added 5 mpg to average in around town driving. More fun, too.
I have an idea why this is happening, not sure tho. The experiment you conducted shows that gentle accelaration is the way to go for turbocharged petrol cars. And i say that is expected since almost all turbocharged cars put their max torque around 1500-2000 rpm band. But lets say you are driving a naturally aspirated car which most of the give their max torque around 4000-4500 rpm, it is best to full throttle and reach that RPM band. After reaching desired speed, you can drive at normal rpm's.
Well, that explains a lot! I have a 2020 Toyota Corolla hatchback with a 2.0 liter NA engine. I've noticed that I get far better gas mileage when I really get the engine revving before I change up a gear. Like, 4,000 rpm, as you mentioned (with the exception of 1st gear, I change up into 2nd as soon as I can). My car's normal rpm is 2,500 or so. If I change up at 3,000 rpm, I get fewer mpg versus waiting till I reach 3,500 or 4,000. I had long been wondering why I get better mpg when I accelerate more aggressively, and now I know why!
I would like to test an NA engine, but as I understand it, wide open throttle at low RPM in an NA engine will have a higher efficiency as there are less pumping loses and the fuel mixture will be less rich than a turbo.
The only logic I can think of is the reduced pumping losses when your throttle body is wide open. But that alone does not make high acceleration efficient. Wheel slip (much of which cannot be felt), high RPM (more heat loss and less efficient combustion), and the likelihood of running into some kind of obstacle requiring braking sooner (aka, over-metering fuel for given conditions) all make accelerating quickly nowhere near as efficient as gradual, linear acceleration. Love your content!
But if you still shift relatively early and have enough distance to fully lift and coast, a hard-ish acceleration should be the most efficient option no?
Definitely need to do this in an NA car. At the low RPMs the turbo is not spoiling much and you're not dumping in extra fuel for power and cooling to prevent knock. Turbos ruin fuel efficiency. I expect it would be closer in an NA car.
Ok I might be that guy that uses the lower rev torque of the engine. I modified my auto to manual shift so it holds every gear I select. Because factory cruise control wants to maintain speed up hills And this makes a normal automatic drop back in gears sooooo I also added a throttle holding lever instead of the normal cruise With this set up I can set the cruise for 80kmh put have the throttle holding 90 on a flat straight. This let’s it go a bit faster down hills but reduces speed slowly As it goes up the next hill until it reaches the 80k when cruise takes over to keep up the pace, on average I still get to places within reasonable time and reduce fuel consumption by up 25% on some runs. and yes as I know the lever position for cruising I can use it for acceleration as well keeping within the lower rev engine loads. Now I am researching how to make this into a simple automated system were as if I any situation I choose I can set a cruise like factory but it would be a soft cruise So for example I choose 90kmh then the throttle would only increase as it slows up hill until it reaches 80 But would reduce above 90 to 100 when there would be zero throttle position. So basically it would not be hunting a target speed as normal but rather operating within a range.
Breaking is a big fuel consumer too for the energy spent to get up to speed only to lose it again to the heat generated by the breaks, lifting early does save gas. Gently accelerating and decelerating is the answer to an efficient and comfortable drive. Looking ahead of the car and a 360 situation awareness helps as well.
There has to be a balance between engine RPM and efficiency, which is offset by time spent at lower speeds and offset by drag coefficient at higher speeds. Really interesting video and well thought out, thank you for sharing
For an electric car, the less you press the go pedal, the further it will travel, your electrical losses are the square of the current times the electrical resistance, from which it follows higher load due to air resistance at high speed drawing more current, & high current from accelerating fast are both your enemy.
It would be interesting to see how naturally aspirated cars would compare in this test. I wonder if the results would be different considering turbo petrol's run richer under hard acceleration yet support the engine better (more fuel efficient) at low loads.
I have an eighteen year old, SLK 350. Sport returns a better MPG than comfort mode. I've not tested as exact as this but slow speed destroys my MPG. I'll experiment more at a later date,
@@JohnPaulFoster I'm not sure myself about the sport/comfort thing. I'm not surprised you get bad mpg showing slower/ in traffic etc because you've got a big 3.5l V6. Bigger engines like yours would be at their most efficient in top gear on the motorway, with alot less of a penalty for going 70+ mph compared to smaller NA engines. A bigger engine doesn't have to work/ rev as hard for faster cruising. Due to its size it will burn more fuel in the slower regime because the extra capacity is largely wasted.
If you want to save fuel when going to A and B just ride a small cc motorcycle like a 125cc~150cc and is also so much fun. I rev the heck out of my old 2006 CBR150R to 8~10K RPM and still gets around 20~25 km/l if I want to save fuel I can get around 30~35 km/l. There even more economic motorcycles out there, fuel is so expensive right now...
I had fun with this video, but this is a very complicated issue and I don't think it can be covered in a few minutes. but hey entertainment is the aim here so good job. :)
I drove a 1.4L Clio for a few years before getting my 1.4L TSI Ibiza, coincidentally it looks like it has the same engine as Richard’s Leon in this video. From my experience, the slower (non turbo) Clio was much more forgiving on full throttle. I could spend a good portion of the journey giving it all she had (which wasn’t much) and not have to think twice about the MPG which usually came out around 39-45. It never strayed away from this figure regardless of how much or little I tried to drive efficiently. I guess you could say the “spikes” in consumption were smoother. The Ibiza on the other hand varies much more. A gentle drive can see me around 48-55 MPG. A faster drive could drop the MPG right down to 38 which is a huge difference. I’ve found the turbo engine to be more fuel-efficient but *only* when I wanted it to be. By comparison it drinks a lot faster when you want that extra performance.
@@joshuatk59 What's the difference in power? did you factor in braking? If you are driving faster and braking from higher Vmax then you are also gonna put more energy in to heat.
Skoda Fabia 1.6 16V (77kW) non-turbo petrol.... I work in town 18 kilometers from where I live, there are 6 villages on my way to work stuck together with just few km between each of them... I can get around 5.8-6,1l/km riding 50km/h in 4th gear (around 2000 RPM), giving it full gas after leaving the village shifting into neutral at 80km/h or 100km/h (a bit over but my tacho reads +5km/h) and cruising into another village.... I can get around 6.1-6.7l/km riding the same speeds, getting feet off the gas and leaving it in the gear (I have my spots to ease off and to get around 55-60km/h entering the village (city speed limit is 50 +-10%) but not being in the neutral literally half the time... Accelerating to around 70-75km/h and shifting into the 5th at around 2500ish RPM and being a bit gentle on the throttle accelerating all the time... And by the way, look at that... the car in video suggests you to shift into the next gear at around 1800RPM, which just looks silly in car with TURBO.... jesus
@@joshuatk59 turbo engines have always been more thursty in the town traffic compared to NA engines, but in comparison the turbocharged engines have a nicer power delivery and better economy if you drive smoothly
Solid video! My whole driving style is based around driving it eco, but at the same time not being a grandma on the road. I still drive the speed limit and try to set an example, however I rarely accelerate slow, even if it might cost me a bit extra fuel. And I am not talking about driving it like I am racing either. Starting off a traffic light or stop sign I accelerate half throttle and change at around 2500-3000 RPM (maybe 3500 if I am feeling a bit rowdy) and go trough gears 1-3 and just accelerate to the speed limit (50km/h) and just drop it into 4th gear, rarely into fifth if I am driving on a wide and straight boulevard. My reasons being: 1. I don't want to feel like a snail around people and angering them (I've driven behind people which hold me in 1st gear for a solid 10 seconds and and the car jerks around it's a bad experience) 2. I like the sound that the cone filter makes when I press the pedal half way trough so it brings me pleasure when I drive around instead of it being a chore. 3. My throttle is cable driven so I get most of my torque with 1/2 throttle or even 1/3 throttle, compared to drive by wire. 4. I am hoping it reduces pumping losses and helps me get up to speed quicker and try to have good brake specific fuel consumption so I have more time to cruise. 5. It's a 98 civic with a small 1.4 liter N/A engine. Although I messed around with it and modified it it still feels in it's happy zone above 1500-2000 rpm, bellow that you feel like it's dragging it's feet. Hence why I rarely let it fall bellow 1,5k. If I dip bellow that I simply rev match and downshift. Small turbo cars or cars with bigger displacement that have good low end torque allow you to accelerate easier on lower revs, but small N/A engines lack that so you need to rev them a bit more to bring them to life. With all that being said most of my slowing down is focused on anticipation and letting the engine slow down on it's own if you are nearing a red light for example and there is traffic ahead. Even if you accelerate gently and don't speed to much, most of you economy is lost when you overuse the brakes. Hence why I was getting good economy before even when I was pushing it around (Around 5.2/5.3 L to 100km with most of my trips being 80-85% rural driving and 15-20% urban driving give or take). All in all it's really the best of both worlds. With moderate throttle and anticipation you still make the driving experience fun and engaging while maintaining good economy + the added benefit of reducing the risk of people behind you getting impatient and doing reckless overtakes and all that. You can't escape them completely, cause some people will always be "in a hurry" but it reduces those encounters quite a bit. Cheers!
Overall less than half-throttle seems ideal I think in order to find the efficiency of the engine at each rpm is to try going Long distance uphill only, say from 1k to 4k and in between (1500, 1800)
Bear in mind in this video I wasn't trying to find the most efficient RPM for the engine. I was trying to find the most economical way to get up to speed.
Being a family man and driving in Bengaluru, I'm criticized for slow acceleration. Earlier I'd claim it was because I love my family and accelerating slowly gives me better control over a chaotic sutuation (bikes + cars+ autos swarming all over when the lights turn green. Now I can say it helps with fuel economy 😀
Accelerating gently not only helps with fuel economy, but it also increases the engine lifespan. It has many benefits but accelerating too slowly can be a problem. It can cause the traffic flow on the road to slow down and may also cause clutch wear and tear if you hold it down for too long (especially partially).
Just please don't be one of those guys accelerating so slow on the ramp that they merging into the highway at 50kph its not safe for you or the people around you.
75% engine load @1,800-2,500rpm is the target for me during acceleration. My car is a 1L 3 cylinder Aygo though so it's pretty slow at 75% load in that rev range... I get Around 72mpg.
For that MPG result, is that In town, combined or motorway? I accelerate quite gently but still acceptable on roads and change at the earliest point possible (usually 1800-2000rpm) get about 55-60mpg in town (where you constantly accelerate and slow down) in my 1.4 turbo diesel hatchback.
@@squeakers27 my commute is around 75% A roads and 25% city. I'm rarely ever out during rush hour though. Funnily enough though I get around 80mpg in city driving and 70mpg on A roads (at ~50mph). My partner has a 1.9 diesel Skoda Octavia and I find it gets opposite results, about 50mpg in the city and around 75mpg on A/M roads. My best ever full tank was this year around the time of that 40°c heatwave at 79.1mpg (it did 494 miles and used 28.4L). I was taking it steady though as the cooling system on the car was struggling to keep up when ever I used the throttle. It was probably unnecessary really as the fan never kicked in anyway but I did see allot of broken down cars on the drive to work that day!
Amazing test, thank you for all the detail. The only info I was missing is the time it took to do the distance, not just reaching 50mph. (though I guess one can measure it from the video 😄)
On petrol engines the air-fuel-ratio changes above ~80% throttle. To get maximum power more fuel is injected (AFR 12.6:1) while maximum fuel efficiency is reached arount AFR 15.4:1. So 100% throttle will significantly impact fuel range compared to
Driving instructors usually say gas as it's quickly. I understand the throttle valve controls air flow, in my MX5 I believe it goes fully open and uses the variable valve timing to control the throttle at certain loads to reduce pumping loses.
Who in their right mind believes that logic? Acceleration uses the most gas so driving with the throttle wide open will use significantly more gas than doing gentle accelerations. Braking only wastes gas if you're constantly braking to slow down then to accelerate immediately after braking
Well the idea is that since acceleration uses a lot of gas, you want to be doing it for as short duration as possible, while taking advantage of the efficient bands of the engine, so high load, low rpm - around peak torque. My theory is that this engine ran rich to prevent knock when he was full throttle and shifting at 2k, and there would be more advantage in a diesel, where knock isn't a problem
@@EndstyleGG that would work for a tuned engine or high performance car from the factory. Most of us that drive the grocery getters won't have any advantage to doing hard accelerations cause those are mapped to just dump fuel to keep up with the rpms since the injectors are small.
@@Kisame663 cars tend to be most efficient at around 50-55 mph. The reason people think it is better to accelerate faster is because you would be at the most efficient speed for longer on the same piece of road. they are actually correct to an extent but can overestimate how fast they should accelerate. hence the purpose of the video.
@@alfaruuto5182 that I can agree with, but it's wild to me to think people believe hard accelerations make any kind of sense outside of race applications when you're trying to save gas with these bonkers gas prices.
Probably if you accelerate like 5 times slower than "very gentle" run youd probably get worse economy, but again maybe and no one will ever do this, so slow acceleration is the key.
The problem with this test is that it's not isolating for average speed. The gentle test has a significantly lower average speed, so this test really just confirms that lower driving speed is better for efficiency.
I want to see you try this again, but always shift at the same rpm, for example full throttle but shift at 4K, half throttle but shift at 4K and gentle acceleration but shift at 4k
The real secret to saving fuel during acceleration is to floor it but shift very early. Gas engines are most efficient when the throttle is wide open (less restrion in the intake) and the rpm is low (less friction)
Would be interesting to compare different methods that have the same total trip duration: accelerate fast(ish) and cruise at a lower speed or accelerate slowly and cruise at a higher speed. And all that for as realistic a trip as possible: several accelerations and decelerations etc.
Nice video, but note that results will be different on a NA vehicle. A turbocharged engine changes timing and fuel mixture under boost to prevent pre-ignition and that results in lost efficiency. NA engines are much different BSFC curves.
thanks for confirming my theory. been driving professionally for 3 years, had debate with other drivers which driving style uses the least fuel. i think I can say I won the debate with this video. i drive gently, but I still get to the destination on time. that's what matters anyway, being on time.
You've missed the actual magic combination. For gasoline engines use full throttle but, take a look at dyno graph at maximum torque: For N/A you'll see it peak and you want to use that peak both slightly after and slightly before it, so switch gears accordingly. For turbo check where it starts to be close to maximum and switch gears so that it doesn't fall below that. Keep throttle pegged when accelerating as it will amount to maximum air put into engine, ECU figures the gas required and engine is less efficient and less powerful = less fuel at lowest rpm, most efficient, moderetly powerful at mid rpm and than it just dumps fuel and is most powerful at highest rpm. With N/A VVT 2.0 you can expect smth like (fuel per 100km/power/RPM) 5l/15KM/1000RPM, 9l/130KM/4000RPM, 20l/150KM/6500RPM.
Accelerate gently at high RPMS, to get to that consistent speed over than acceleratin hard at low RPMS. Imagine having a diesel and changing at low RPMS, in time, that engine will get broken
Best thing to do is to look at brake specific fuel consumption (BSFC) graphs for your car (or plot some yourself using OBDII software). Most cars have the best power:fuel consumption ratio relatively low in the RPM range, just below peak torque, at around 60-80% throttle position (depending on the load). Every car is different. One on-the-road hypermiling technique is to accelerate close to this peak power:fuel ratio regime until you're at your target speed. OBD2 software live readouts and practice can be used to get good at this. There are tons more hypermiling techniques I'd love to see you test out, such as pulse and glide. This is where you take advantage of the better efficiency at higher loads by accelerating harder then coasting (or partially letting off the throttle for an on-the-road technique that's usable on public roads) then repeating, rather than holding a set speed. Another hypermiling technique I'd love to see you try would be invreasing throttle going downhill rather than uphill. This is where accelerating downhill is more efficient (since gravity is helping you), then allowing the car to decelerate going uphill (with some even coasting when going uphill). Cruise control basically does the opposite of this by trying to maintain a fixed target speed.
Ive always been gentle with accelerating and braking not so much for fuel economy but just to take it easy on the engines. Does yield great mpg results because of it!
Running an engine at its peak torque under maximum load is always the most efficient, but is not super possible due to vehicle design sadly. This is why CVTs are so good for efficiency. They massively overcome their inherent inefficiency by allowing one to run at ideal engine speed and load continuously as long as the driver is aware of how to get the computer to go to the correct area. Of course, what matters far more is being able to predict and react to road conditions easily. For example, in my dad's 2014 Chevy Silverado, I get 16-20mpg depending on conditions, where my dad gets 14-18. This difference is almost purely due to my tendency to predict timing of traffic lights and avoid stopping as often. The only other significant factors are my chosen cruise speeds on highways and acceleration. I choose better cruise speeds than my dad, but I accelerate harder than I probably should. They cancel out partially.
I don't consider myself a hypermailer, despite doing it frequently. It's just that the 3.2l NA engine loves to drink that gasoline. So if there isn't significant traffic, that 2000rpm is quite the optimal shift spot. But heavy traffic is a bit different playfield, having that potential to accelerate fast gives better safety margins when merging from sideroad.
Most petrol cars I up shift at 2.5K and down at 1.5K when cruising. On a gentle throttle I can beat most mpg figures published by the manufacturer. Its all down to momentum v traffic levels
It's all about ratios. The amount of fuel needed to accelerate a car twice as fast is multiple times more than the fuel needed to slowly accelerate the same car. This is why "eco mode" on cars simply changes the throttle sensitivity, that's all it's doing. It "helps" because you're not mashing the throttle as much, it's a smoother delivery, resulting in slightly increased fuel efficiency.
This testing method is vastly flawed. You a absolutely cannot compare short shifting at 2k rpm versus shifting at 3k or 4k rpm as it will quite obviously use more fuel at higher rpm regardless of duty cycle. Full throttle at 1500rpm is also labouring the engine as the turbo does not have sufficient exhaust pressure to spool the turbo in order to run efficiently.
Maybe on hybrids (like Toyotas), if you want to get on the EV motor as much as possible. Accelerating more quickly (but no crazy full throttle) gets you to cruising speed quicker, so you spend more time on EV. And of course, for braking, it's the reverse, you decelerate and don't break. Let the EV do the regen breaking for as long as possible. I'm not 100% on this, it's more a feeling that the car isn't struggling as much.
@@thefrenchareharlequins2743 that’s a great point. I’m a very calm driver and I never drive fast unless necessary, I didn’t mean that you should accelerate aggressively, that will cause you to waste much more fuel, because of what you’ve said. What I meant was a moderate acceleration (40-50% of throttle). This one is the best for the city, because it will make you able not to miss green lights much more often than if you accelerate slowly, and it won’t use much more fuel (as the video has shown).
