what kind of holder have you installed?

 

The one that came with the GPS unit.

 

I disagree with mounting locations other than the windshield.

The windshield is where your eyes should remain as they look at the road. Having to look down removes your eyes from the road, and causes a driving distraction. I place mine center-low on the windshield, right next to my field of view.

The GPS I use is the Garmin 3790T. I keep it vertically oriented, rather than horizontally. This allows me to see further down the road on the map, since we travel forward in our vehicles, and not to the side. The 3790T is very small like an iPhone, yet the screen is large at 4.3". The screen resolution is also quite high. I greatly recommend this GPS.

 

I have a brandnew 2.4 Instyle and put my garmin left on the dashboard. Fixed the mounting plate for the suction nap with double tape. Take care the dash is round so you need two layers of 1.5 mm tape to cover the rounding. Put it in the middle between the steering wheel and door. Problem which I met, when you are righthanded and have to typ suddenly with left during driving is not very safe. This place makes it possible to look through the frontwindow and to the Garmin. 10 cm of wire to the left and than between door and side-dash down and go in under the coinbox and up again behind the dash. Find a good wire (on/of contact) (with me a yellow one) (grounding can be found anywhere) in the fusebox and ready you are. Looks good and satisfactory.