Franglais:
Already touched on here, but with electric vehicles the energy used in braking can be put back into the batteries.
The energy used to get a vehicle up a bank can be replaced by the energy used to slow it down on the other side. In the real world it’ll never be equal, but will make a big difference in overall efficiency. Just consider all that heat thrown out (wasted) by an engine climbing a hill and all that heat thrown out by brakes and retarder (wasted) on the descent. I’ll have a bet that what takes to the road first will be a hybrid, large batteries, regenerative braking, and an I.C. engine to give a boost to the batteries when needed. And with predictions about the route chosen maybe use the engine to top up the battery before a hill upwards, or allow the battery to get low if a descent is approaching.Sent from my GT-S7275R using Tapatalk
Modern Hybrid racing cars not only recover power from the brakes, but also recover energy from the exhaust system, and a motor connected to the turbocharger which works both in a recovery mode and is also able to spin the turbo up to reduce turbo lag. The F1 regs have reduced the allowed fuel flow to 100kg/h, when F1 stopped using the 3l engines they required a fuel flow rate of around 190kg/h. I’ve spoken to drivers who’ve moved from normal racing cars to the hybrids, and they say the main things they notice is the instant acceleration from the electric motors and the extra braking from the energy recovery system.
Mercedes have just launched the Project One supercar, 1000bhp from a 1.6litre hybrid engine 
taken directly from their F1 program.
Imagine the energy recovery possibilities of a modern 13litre diesel engine and the saving on fuel costs and the extra torque for hill climbing or pulling away fully loaded?
The only thing for me having seen the procedure for making the car safe for transport and the procedures in place to deal with battery and ERS problems, is the amount of power in the system if something goes wrong.