We can do the next best thing.
1/2 mile (800m) ahead, I see a light turn yellow; at 60 mph (100kph) that's 30 seconds. And I know that light has about a 35 second cycle, plus 10 seconds for the stack of stopped cars to get moving.
I've been applying continuous power to keep speed. I will continue doing so for another 25 seconds, then 5 seconds of firm braking and stop. 15 seconds playing with my phone, then I'm on my way.
Or... I go to idle power immediately. My car coasts. With the engine still in gear, my momentum is pushing (spinning) the engine, for a mild braking effect, so the fuel injectors shut off entirely. My speed gradually slows... 55... 50... 45... Little bit of power... 40 (65kph)... flip the light turns green while I'm still 1/8 mile (200m) back. The stopped cars unpack and I gauge exactly when to apply power. And I never brake.
In the first scenario, there are two energy exchanges. First the fuel applied for that 3/8 of a mile (600m) to stay in cruise. Second, the braking energy shed in the last 1/8 mile. Not only are these nearly equal, they are the same energy. If we were doing proper regen, we could read them off the ammeter and derive the actual joules out and in.
In the second scenario, there are none. Fuel is not expended and brake energy is not shed. The effect of regenerative braking is achieved, but without any conversion losses.
Granted, this is an education approach rather than a technology approach, but it works. Even on an EV capable of regen, it still works better than regen - in fact it'll work even better on an EV because you get better "coast" - no need to use drag to spin the engine merely to provide brake and steer assist.