We carry our bikes that way (except forks to the back) in the back of my Explorer and the back of bf's Saturn Vue (although, he has to drop his saddle a touch for the Vue). When carrying other gear, we slip wheel bags over the rear wheels to cover the cassettes and keep things a bit tidier. Front wheels go into wheel bags for their own protection. We've actually used this method with 3 bikes + gear, with bike in the middle fork toward the front.