If i remember correctly, electric cars have regenerative breaking systems that is, upon breaking, there is a component in the car that traps the energy it can get while breaking and convert it to useful energy the car can use while running. The problem, with these cars though, is the battery. I hope they could device ones that would be efficient, cost-friendly and higher capacity to reduce the risks of breaking down in a free way, which could be potentially dangerous even though smart cars have their own lanes.