I saw the concentrating sun idea on you tube a few years back, where a guy demonstrated a clunky homemade version on a very small scale. It worked pretty well but was roughly constructed. I remember thinking that if they could somehow incorporate small lenses above or in each solar cell it might be more practical.
Just like the batteries.... With current day technology the solar panels are still too inefficient.
However if the car sat 6-7 hours in good sun you might get 1.5 -2kw not too bad.