AI trained to control traffic 

Seriously. But, I think it's still worth it. Any efforts to encourage more space and more elasticity of cars on the road will help, even with the maniacs that can't wait to use more gas to get 15 feet further than they'd be otherwise.

Keep the space but just barely not enough to fit another car, it drives people mad but it should work.

If you're maintaining a safe distance, another car should be able to merge in without issue.

"Dream on AI proponents." It's coming whether you like it or not, idiot. Especially because dumb meatbags like you are incredibly inefficient, arrogant, and slow.

Can't agree more, part of the problem is that the lack of ownership of cars given autonomy becomes wide spread; the argument is : if they are self driven, then the next argument is why posses it if you only use it x% of the time ... hence now everyone is subject to a transportation vendor that you pay over, and over, and over... But being robbed silly for life isn't the problem but rather living spaces. While you can argue that parking spaces are "returned to the community" fact is, part of our living space is secured thanks to cars. Many startups began their life in garages (as well as laboratories, music groups, etc). This means that population dense areas will have even less space for themselves or between themselves as this is no longer a necessity. Sure, there's the fact that it is far to tempting to hack the system given how much return on investment that would give. But there have always been predators, but having people bombarded by commercials(just like AM, FM, and the internet; you have people held hostage to adverts ... again), segregated by means of zone access protocols (imagine a virtual gate at every point of the city with routes depending on travel plans), and sections of people packed worse than sardines (again no need for roads, parking spaces or garages so you can now enjoy living in a tiny box probably hearing your neighbors brushing their teeth quite clearly) is something that I just find hard to accept as progress in any way

That's why security is a top-notch priority in the age of AI and IoT. Don't ever let unwanted parties take control over this technology. Also, the programmer should be more wary of bugs in their program because of how devastating it would be if it accelerate at maximum speed instead of hitting the brake when faced with pedestrian.

While not much higher at first look, it could be huge in massively populated cities, especially since traffic jams can be the start of other ones.