Preferred GPS antenna location?

[GTIspirit]

I was originally thinking of mounting the GPS antenna on the roof of my car, out through the hole for the radio antenna that is no longer necessary. I remember seeing some kind of inverted magnetic cup that covers an external GPS antenna and holds it to the sheet metal of a car. But then I got to thinking, maybe I'm making it too complicated, what about just sticking it on the dashboard as far forward as possible? What locations have people found to preferable or not?

[brentp]

Dashboard or roof of the car has worked for us. We've also placed it on the flat surface of the rear hatch in our XR4Ti race car. As long as you have a good exposure to the sky you should be good!

There may be some measurable performance differences with the unit outside vs inside the vehicle (where metal in the car may partially obstruct the signal) - perhaps someone will take some measurements for us.

[ddeltoro]

I put mine right in the center of the car on the roof, just ran the cable out through the door and the weatherstripping that was there offered enough cushion. Very happy with the strength of the magnet on this thing, I was only doing maybe 70 during the autox but hard acceleration and it never budged.

[GameboyRMH]

I'd like to have mine permanently mounted inside the car and under the interior panels, I was thinking near the front edge of the dash or rear edge of the rear deck would be best, this will put only a couple of thin layers of non-metallic material between the receiver and the sky unless you're driving on a very steep hill. In my 4x4 I use a navigation program running on an old PDA with the GPS receiver in my glove box and it gets a good stable signal.