It’s never a good idea to load a mattress on top of your car. Not only are you exposing your mattress to things like dust, dirt, and wind damage. You’re also setting yourself up for a nasty accident that could damage more than just your mattress.
It’s easy for the wind to get up under your mattress and flip it off your car. When that happens, the mattress is almost certain to be damaged beyond repair. It could also hit other vehicles and cause serious accidents. That’s why you should always move your mattress to its new home in a large SUV, a moving van, or a pickup truck with a bed cover.