I had the same issues until I purchased a new type of plug (mini USB adapter) that accepts USB jacks. This plug inserts fully into the cigar lighter, and is flush with the outside edge (allowing me to close the ash tray when not in use). The USB plugs now come with an endless inventory of adapted ends (Apple devices, Blackberry devices, etc). I got mine at WalMart...

Resulting in no more wiggle issues!