I use a older Hollywood hitch rack on my Van. It carries two bikes and can be converted to carry four bikes. The bikes don't hang by the top tube, instead they sit in a track and an adjustable bar swings up and grabs the seat tube. Adjustable straps secure the wheels to the tracks. No banging bikes, no spinning wheels, and the rack swings down to allow access to the rear doors.

I've also got an old Yakima roof system for my car which I love. Same idea, bike sits in a track and an adjustable bar swings up and grabs the down tube. Disadvantage..the older I get, the tougher it is to throw the bikes up onto the roof of the car.

Whatever you buy, make sure it's good and strong...the 18 wheeler behind you may not be able to avoid squishing your bike as it bounces down the interstate at 65 mph.