Danielle's car has blue background/gold lettered California license plates. California stopped making the blue/gold plates in the early 1980s. Her new style Beetle has to be a 1998 or newer. The only way a car that new can have the blue/gold plates is if they are personalized plates which go with the owner. The plates on Danielle's car are not personalized with a special word.
There are a few songs that play at prom, however it could be "Lucky Man" by the Verve. The rest of the songs and their corresponding scenes can be found here at what-song.