I've read a lot of useful posts regarding the merits of hitch-mounted bike racks vs. roof mounted, but no one has mentioned whether it's harmful to the Prius to have all that weight hanging off the back of the car. My other car is an aging Subaru Legacy. We put a hitch on it and bought a heavy (and I do mean HEAVY) duty bike carrier for it. With four bikes in the rack, the poor car looks like it's permanently heading uphill. I worry about its effect on the car and wonder if the same thing would happen to the Prius if I put on a rack and loaded it with four (the minimum number for my family) bikes. Also, no one has mentioned the merits or problems of a rack that mounts on the hatch. I have seen one or two Priuses on the highway in this configuration. I'd welcome any thoughts or experiences regarding the effect of putting a heavy load on the back end of the car.