When shopping for a new car, there are lots of options to consider when finding the most fuel-efficient vehicle. One of those choices is the exterior color of your car. A study by the Berkeley Lab's Environmental Energy Technologies Division looked at two identical cars in different colors. One was a lighter silver shade, and the other one was black. When sitting in the hot sun, the lighter car used 13 percent less energy to cool down in comparison to the black vehicle. Overall, a lighter color car -- silver or white -- saves on average about 2 percent in gas and helps extend the life of your battery, too.