Obviously the best place for a nav antenna would be on the roof of the vehicle, however this is not always the easiest place to install nor does it accent the look of a vehicle with an unsightly wire. You can install a nav antenna under any dashboard that doesn't have metal in it, and it will work fine. The other route is to use a factory or aftermarket drill in type antenna as in the GM, Audi or VW vehicles. I purchased a couple of the GM 3 band antennas(XM, GPS and cellular) and installed them, the only catch is you need wire extensions for the portion of the antenna that you want to use. Th