Why just white. Our atmosphere has a 'window' that IR can radiate out to space between 8 and 13 micrometers. There's a surface treatment now that can keep a surface cooler than ambient air in full sun. On a mobile, can't find a link to the coating, but for background check this article in Nature https://www.nature.com/articles/nature13883
As I remember, it's starting to be used in places like the roofs of sun shelters for people waiting for the bus in the American Southwest. I'd just use it on rooftops. Anyone who's spent time sailing (big white reflective sails, white decks, reflective ocean) can tell you that painting *everything* isn't the best idea...