Thanks guys. I would be concerned that the suction cups would leave marks on the paint, but I guess if the paint is squeaky clean before attaching them, it wouldn't be a problem. Now I need to find a bike with an easily-removable front wheel.
I've been using this bike rack for about 2 years and there are no marks on my car. I use a spray detailer to clean the painted surface of the car before attaching the suction cup.
Full Suspension 29er MTB slides in trunk perfectly with just taking off the front tire. Been driving to the trails now for years without having bike rack ruining paint and making me drive slow!
I'll be checking out bikes this week. I want a beach cruiser and I'll try to get one that will fit inside. Otherwise I'll order a Sea Sucker. In either case I'll need a bike with a QR front wheel. Hopefully that won't be a problem.