i have had trunk racks, hitch mounted rear racks and roof racks. Roof racks are by far my favorite. The trunk rack ended up damaging the paint on the rear deck lid of my VW. The hitch mounted rack drags going up or down steep drives. The roof rack does neither and I do not notice decreased mileage with it. Just have to remember you have bikes up there when going thru drive thrus, into garages etc. Also, since bikes attach to most roof racks only at rear tire and fork, or both tires and down tube, they fit a majority of bikes. Bikes attach to most rear mount racks by hanging from the top tube, which can be a challenge on small frames or womens frames. In some cases you have to buy a bar that attaches to stem and seat post to make a "top tube" to attach a womens bike.