Thanks, I didn't know engines specifically cut down the fuel supply nowadays when engine braking. I'm not sure charging the car battery used for lights etc counts for much though!

I do think this is significantly different in ICE cars from regenerative braking in EV cars which actually stores the energy and can use it to drive the engine later. This still comes out ahead against ICE cars which don't burn much energy while going downhill.

There's a lot of electricity-driven stuff in ICE cars these days. For example in my car AC is running off car battery, not directly using the engine. When driving in city, start-stop turns off engine at traffic light and AC keeps going.

Regenerative power for starter in frequent start-stop cycle must help a lot too.

Lights do add up too. I remember when a good decade ago day lights were made mandatory all around the year all day long. Very few cars had LED daylights so most people had to run dipped lights. Some people did backyard tests that lights add 0.5L/100km or so. Obviously now LEDs are much more efficient. On the other hand, infotainment system is ever bigger beast. But if regenerative braking power can take off the edge... Why not.

Anyway, I'm not saying that ICE is better than EV. Just saying that ICE can make use of regenerative power.