I use the Thule Crossroad set with the 50in square bars on a Chevy HHR. The Crossroad "feet" secure very well to the factory rails, I thought it would be a little shaky but it wasn't at all. With the rails/bars installed, it is only slightly louder on the highway than normal but I honestly was expecting the noise to be worse. (obviously, the HHR is not the most aerodynamic vehicle and it has it's fair share of road noise naturally.) I have noticed about 1mpg decrease for highway fuel economy with the racks installed (and no bikes on it) but nothing that bothers me. I expect it to decrease further once we get the bikes up top, but I prefer this option over our carbon forks rubbing together on a hitch rack.