If you go with the roof rack on factory installed rails, get the Rocky Mounts tray...those are good ones and available in a choice of colors. They are strudy enough and safe for bikes. A firing in the front is highly recommended to reduce wind noise. And mileage will drop.

A trunk rack...sooner or later you will scratch the paint, if not from accidentally scraping against it, thru road grit getting in between the rack contact point and the car body (ask me how i know!)

I'd recommend the hitch receiver+ mount solution anyday.