A buddy recommended one of these:
http://www.ecshylites.citymax.com/page/page/761353.htm

I have used one like this with good results and you can usually find one at you local autoparts store:
http://www.thehoffmangroup.com/autol...odinc=antennas
I had mine mounted to the roof under the headliner. They run about $40.
But have seen one mounted under the front bonnet of a beetle with double sided sticky tape. However if I remember they don't like direct contact with metal.