Well I have a Scion Xa myself and use the Saris Bones. If someone does rear end me then yes my bikes will be wrecked, but the car cost me a lot more heh. I've yet to see a bones strapped to a Xb so not sure how it would sit on one, but I know you can adjust the levels on the bars a lot so I'm sure you wouldn't have to worry about the bikes being too low.