To clarify my reasoning in asking for the registration number, I didn't think this would be much of a puzzle if just asking for "VW Eigenbau" as the answer, since that is almost the default answer for any car that looks like this so shouldn't really earn the point.
I asked for the registration number just to force some searching to be done and to show that the solver has in fact found the car rather than just guessed the answer.
The registration number can't of course be seen in the puzzle picture so below is the picture on which it is visible; the puzzle is open again if anyone can find it!: