Efficient traffic convoy system

Starting and stopping at stoplights is a waste of energy, also it takes time for long group of cars to accelerate once stopped at a stoplight.

What would be better is to bunch up vehicles into a convoy all following the nearest 'virtual pace car'. Cars just ahead of the virtual pace car would slow down to get closer to the pace car, while cars behind the virtual pace car would speed up to catch up.

Within limits of course, never go above the speed limit to catch up, rather simply slow down to the next virtual pace car behind them.

The virtual pace car would be synchronized with the stoplights; the lights turn green just as it approaches a light. The cars will be bunched together so it wouldn't have to stay green for long to get a bunch of cars through. This will let cross traffic enter more often.

The virtual pace car can simply take a form of signs that simply indicate whether you should slow down or speed up to catch up to the nearest virtual pace car. Brakes and energy will be saved, smooth driving the whole way!

https://en.wikipedia.org/wiki/Traffic_light_control_and_coordination
https://en.wikipedia.org/wiki/Green_wave Same as convoy idea
https://en.wikipedia.org/wiki/Speed_sign Same as pace car idea