There are major noticeable differences between the VWs used in the film: The car starts with a blue-ish interior but throughout the film the interior is yellow at times and the car itself changes from LHD to RHD frequently. The model also changes most notably when Dudu's falling to bits down a hill as the Bug we see doesn't have the sign on the side and has an oval window (1954-1958 Beetles used these) but also when the body is complete off the Bug the body is suddenly a very faint yellow (as opposed to being bright yellow) and there's an obvious missing section in the roof as the car used was probably a junked sunroof Beetle. Dudu also looses his (her?) hubcaps but regains them in the next shot.
It's obvious that a remote-controlled toy version is used for some shots of the VW Käfer.