Re: "an electric vehicle does allowing you to recover most of the energy you expended"
"Not really. As specified here, regenerative braking is not sufficient to bring a vehicle to a stop, so friction braking is still needed. That means that you lose electricity on the energy used by friction, which is substantial because "mechanical braking is still necessary for substantial speed reductions".
In short, regenerative braking is a nice-to-have side-effect, but you will not be driving around nearly indefinitely with just regenerative braking and a PV-covered car roof."
Most new EVs have a "one pedal" mode that will bring the car to a complete stop without using friction brakes.
There are always loses converting from one form of energy into another. Batteries can only absorb so much regen so an emergency stop from 100km isn't going to put as much energy back into the battery as a gradual slow down. PV panels are so inefficient that putting any on the roof of the car or the top of the truck trailer isn't going to make much of a difference in driving distance. About all they are good for is running a fan during the summer to keep the temp down in a car parked outside. All in, regen still works pretty well and can greatly extend the life of brake shoes since they are mostly used at slow speeds.