What you are describing, for it to be of actual benefit, is at its minimum a perpetual motion device, as that's what a zero loss system would be. Only people working on that also sell snake oil.

Anything less than 100% is a loss, which is going to be larger the heavier the car is due to friction (aero, drive train, and rolling) and extra energy to accelerate, that's basic physics.

Very large batteries, 100kwh or over, solve what should be a medium term problem, they are an expensive dead end as they are often around half the cost of the car's production cost and add . What I really don't like is stupidly large bricks of cars that struggle to even do 3 miles per kwh and then use a massive battery to get around their comically small range, which further lowers their efficency.