ONEVAN 150Bar Burshless High Pressure Car Washer 

Actually that's NOT the difficult part, you can achieve that pressure with a VERY SMALL amount of water...and that won't help you in the slightest when washing your car. What you really need to look for is if high pressure matches HIGH WATER FLOW.Technically the blue variant of this device promises a flow of around 380 litres/hour whereas a AC power plugged... medium valued one goes around 500, at 200 bar.Most, and I mean 99,99999% of the cordless washing machines I've researched (and I did from cheapest to over 1500 dollars ones) don't promise more than 240 liters/hour of water flow. I actually own the Onevan, blue variant that(presumably)goes up to 200 bar and I must say it's impressive