[lyner]

light or not you will just be taking the energy u already produced for one reason and use it for another. this would most probably leave ur initial reason for producing that energy at a very big loss. also taking energy away from brakes will lead to their not working as effecients. car makers go out of their way to add extra energy into their braking sytems (eg bmw, heating the brake pads before the brakes are to be applied). you must produce heat in order to stop a car. if you make a system that somehow takes that heat away then there must be some performance that is decreased. producing a system that is more effecient in getting energy out of the fuel is the only salvation for mother Earth.

That is rather mixed up. You do not 'need' heat  to dissipate KE; the process of simple friction braking just transforms the KE into thermal energy  (cause and effect  are the reverse of your statement). BMW use a practical solution for increasing friction,I guess - it's not fundamental.
The acceleration and braking cycle, will not be efficient, of course, but regen braking can help.