I don't currently use an in-vehicle mount for my iPhone. I've tried a few before, but each time I was more than disappointed with their build quality. But if I was going to try one again, I'd probably look for something like the eleMount.
The eleMount is a CNC machined all-aluminum mount for smartphones and tablets that looks like it was crafted by Apple itself. The best part, though, is that it doesn't use suction cups or clamps for mounting; it uses polyurethane pads...