Re: "Key to the car's economical performance is the braking system"
"When you stop a 1.5 tonne vehicle"
1500kg at 40mph has 237kJ of kinetic energy. Come to a complete stop recovering with 80% efficiency and you get 0.053kWh. Need to do that 570 times to charge the battery from this years leaf for example. Thinking of my last car journey of around 50 miles I don't think I braked more than 40 times and less than 1/4 of those to a standstill.
I would still call that close to sod all and certainly not the "key to any car's economical performance".