On a car…YES!
Ceiling white specifically, not just any old white paint; go to a paint store and get Ceiling White, which is practically ideal for the task—it reflects very nearly 100% of the light hitting it. Regular white is down in the 60% range. An example is 'Ceiling Bright White' from Sherwin-Williams; they'll mix it up for you as a polyurethane-based paint on request. It's water-based, so it won't stink up the place and it's easy to apply and clean up.
