Re: Centerpiece for wheel
The so called center caps are available from dealers, I picked up four for about $6 each for my spare wheels. The same center caps are used on both the 18 and 20 inch wheels, I dunno about the 17s. They snap into place, just press the new ones in.
The dealer should just give you one, part of his good will. If you've had the car less than a few months, should easily be covered under warranty. They are not suppose to fall off, but have been known to be stolen... or more often one of the tabs crack when they are installed roughly, and eventually the cap just falls out.