When the Alternators/Binaltech line of hyper-realistic Transformers was being developed, fan favorite Bumblebee was to be recreated as a new Volkswagen Beetle, according to prototype art in "The Transformers Binaltech & TF Collection Complete Guide".

According to Hasbro designer Aaron Archer at "The Official Transformers Collectors Convention" (or OTFCC) '03, Volkswagen had refused to license an Alternator Bumblebee. Volkswagen refused to license the car, however, supposedly due to the warlike nature of the Transformers. [[1]] Since VW was hit hard in 2002 by a lawsuit by holocaust victims for their involvement in WWII (as a German manufacturer), VW is understandably reluctant to have its name tied to anything that could be considered a war machine. Hasbro had agreed to not give Bumblebee a gun, however, the prototype shot given to Volkswagen still had the gun present. Volkswagen were unaware that the picture was a prototype and they rejected the idea

This explains why the Bumblebee Altmode does not exist as a New VW Beetle and instead as other form cars beyond the old VW Beetle model.

http://en.wikipedia.org/wiki/Bumblebee_transformers#Volkswagen_New_Beetle_model