I have a convertible so I can't use a roof rack and my car style is such that I can't add a hitch, so a trunk rack is my only choice. I got a Saris Bones two-bike rack and couldn't be happier with it. No damage to the bikes or the car if you make sure that the pedals are lined up so as not to touch each other or the car. My husband came up with a way to lock the bikes to the rack and the rack to the car and the cable also keeps the wheels from spinning but bungie cords would work as well. It's also easy to put on and remove and has six straps that hook to the top, sides, and bottom of the trunk lid.