Try "The Love Bug Rally." That's likely to be your film. I've had it on my want list for a while.
EDIT TO ADD: Looks like this is likely the third (yikes!) entry in this German copy of the Herbie movies, no official English translation for the title:
Ein Käfer auf Extratour (A Beetle on Extra Tour)
IMDb link:
http://www.imdb.com/title/tt0070280/