If you buy the $39.99 TomTom App for your iPhone 4, chances are you will need a holder for it. That's when you buy the car kit. Turns out that the iPhone 4 is a bit slimmer than the past models, so now it doesn't quite fit into your car kit correctly. What are you to do?
Looks like you can get a free iPhone 4 adapter. Here is the info according to TomTom's website:
In order to have your car kit for iPhone work with iPhone 4, you need the adapter for iPhone 4. This is included in our packaging from September 1st 2010. If you have bought a car kit before September 1st 2010, you can claim your adapter here
Just in case you needed your iPhone 4 to sit tightly in the car kit.