Universal Roof Cargo Box by Car Top Cargo®. When you’re traveling, you want to relax and enjoy the ride – not compete with cargo for space. Heavy, bulky items such as luggage, strollers and outdoor equipment can make your road trip a long one. The Car Top Cargo carrier creates more room for both you and your gear. Durable 4 season HDPE construction combined with an aerodynamic design that helps to reduce wind resistance and aids in fuel economy.