Your phone can be mounted in front of the driver to provide driving directions.  I found the iPhone maps more reliable than the cars' maps.  

I mounted it easily in an older Ford Explorer and in a Lexus ES350.  It needs a ledge about 1 - 1-½" thick x 5+ " deep.  A bolt in the top can be tightened to secure it to the ledge.  Nuts are included to tighten the bolts, but I did not need them.  The shorter bolt is an option to the longer bolt.

The mount can be swiveled toward the driver's line of sight.

The iPhone holder has a built-in bolt that screws onto the mount that goes on the instrument panel ledge.  The connection is tightened with the nut.

My wife's smaller iPhone fits in the holder but may need a rubber band to secure it from falling out. Or, if tilted to the side, it should stay in place.  I may be able to make a smaller holder for the smaller iPhones in the near future.