Can a full size mattress fit in a toyota rav4?

Depending on whether or not You plan to use the mattress in the back of the Toyota RAV4, the question has different answers. You should be able to transport a mattress just fine, on top of the wheel wells, with either the seats moved fully forward or with the mattress folded a bit at the edges, long ways. If You're looking to take a nap back there, it's a no go. Since You'll be sitting on top of Your wheel wells, You won't have the support You need. Additionally, the length will present some challenges. Presumably You're just trying to transport, in which case it will be a right fit -- but with a little bit of folding and elbow grease, You ought to be able to get it done.