Bought a Tomtom the other day ...how the heck do you mount this thing? The only way I can see it working is putting it on the windsheild but I'm sure a cop would pull me over for that.
As long as it is not mounted to where it would obscure your vision you should be fine. We usually mount ours to the lower center of our windshield immediately above the dashboard. They should have something you can buy if you prefer to mount on your dashboard. I don't know exactly how to describe it though.
They also make weighted soft cradles, in case you don't want to drill holes in your dashboard, or apply double-sided sticky tape. I'm not sure how well the weighted cradles will fare in a collision, though. Not sure if the GPS unit will stay put or go for a flight.