I haven't got an IPhone, but have the Brodit Touch Diamond mount, coupled with the centre mount for the leon.
Its not cheap but i have had Brodit mounts for my past few cars and phones and have never been able to fault the quality - I have also bought from the company before and never had an issue.
Edit - i cant post a link due to the number of posts i have made, but if you google for dsldevelopments, then have a look at the Brodit holders you should find what you want.