I use a RAM mount and it works awesome! Very little bounce when taking video on my iPhone. I mount it under the rear view mirror and I have pretty good visibility still. It also holds extremely well. You'll see a lot of good reviews on it for track use and what not.
Amazon.com: RAM Mount X-Grip Composite Twist Lock Suction Cup Mount: Cell Phones & Accessories
I bought a slightly different version but it gives you the idea. Plenty of reviews on the product.