Mine is hooked to one of the metal supports in my Fantastic Fan vent. That way the antenna is out of the rain and windstream but on a pretty hit point. You probably could also run it through the hole for raising the TV antenna and place on an antenna bar. Problem is the wire is dangling in the front cab because our XM is a portable unit that we use outside and in other cars.
Problem is the C Body has no metal for the magnet to hook onto.
You will still have trouble if you travel through a forest area with trees on both sides. Also going north near Canada is a loser due to the satellites being tuned for mid and southern portions of the US.