As mentioned, all trunk-mount racks will leave a mark in time. The only alternative is hitch-mount.
Keeping in mind that I don't even own a car, I own a Saris Bones 3. It is likely the best trunk-mount rack going. It holds the bike stably and far enough away from the car. I add a bungee between the front wheel and downtube to reduce front wheel flop. I've used it on sports cars, sedans, minivans and SUVs. Very versatile mounting, and just the ticket for someone like me who can't predict what sort of car it will next be used on.
Then my parents went and bought a Buick SUV thingie (Enclave) with a plastic spoiler atop the hatch. The Bones won't work on that. So I now also own a
Yakima Hold-Up hitch rack. Weighs an effing ton. But jeepers, it laughs at road bikes.