Won't work for most cars in cities, as they will be parked in indoor/underground garages, so no solar to speak of for their parking time, and the bit of solar you get while driving will maybe power the lights/electronics/audio system at most.

(Driving a full EV, but needing to charge 30+kwh/week, and my small (but larger than a car could fit) home-solar only provides max 20kwh/week in spring/summer.