Chapter 6 of The true story of the Beetle describes how Ferry Porsche - the son of Ferdinand Porsche - and financial director Adolf Rosenberger of the Dr.-Ing. h.c. Ferdinand Porsche GmbH in November 1931 visit Josef Ganz in Frankfurt in order to test-drive his Maikäfer prototype. This passage is of great importance to the story since it means to prove that Josef Ganz was not only a predecessor of Porsche in designing a VW Beetle-like car - but also that the Porsche company based its design of the Zündapp Type 12 prototypes - which are commonly recognised as forerunners of the VW Beetle - on their experiences with and the design of the Maikäfer prototype by Ganz.

The evidence to support this story is based on a few references in historical sources as well as photographic evidence. In April 1944, a German engineer by the name of Armin Drechsel - who knew Josef Ganz since the late 1920s and had also contributed to Motor-Kritik - wrote in a letter to the Swiss lawyer of Josef Ganz, Ferdinand Fuchs, that Ferdinand Porsche visited Josef Ganz on several different occasions in late 1931 before starting with the design of the Zündapp Type 12 prototypes. This claim is supported by Georg Ising - a colleague of Josef Ganz from Motor-Kritik - who suggested in an article in Motor-Kritik in February 1934 how Porsche had visited Ganz in late 1931 and how the Maikäfer prototype had influenced Porsche's design for the Auto-Union Type A racing car.

The article by Georg Ising also contained the first of two pieces of photographic evidence: a photograph of a car which was said to have belonged to Porsche driving off past the Maikäfer parked outside the residential house of Josef Ganz in Frankfurt. Normally, this would be hard if not impossible to prove. However, not if the car in question was the one-off cabriolet built in 1930 for Wanderer with a chassis designed by Porsche and a unique body designed and built by Reutter. Only one of these attractive cabriolets was built and it was owned and used as a company car by the Porsche firm for several years in the early 1930s.

The second piece of photographic evidence was published on the front-cover of Motor-Kritik issue 21 in early November 1931. This shows a photograph of two men sitting in the Maikäfer prototype outside the residential house of Josef Ganz in Frankfurt. The car with the two men is outlined with a white cirkel and the caption 'Um den Kleinstwagen' - suggesting these are important individuals from the automotive industry. Although the photograph is not of very high quality, due to the vintage printing techniques, it is possible to reasonably make out the faces of the two men. These show a remarkable resemblance to Ferry Porsche and Adolf Rosenberger. The person behind the wheel looks quite young with a similar shape of face and haircut as Ferry Porsche. He has a long raincoat on and appears to have a cap in his hand - similar to the dress of Ferry Porsche in that time. The second individual shows a strong resemblance to Adolf Rosenberger, again with a similar, more elongated shape of face and the high forehead and his hair combed back over his head.

All of this coincides perfectly with the history of the Zündapp Type 12 prototypes. The contract between Zündapp and Porsche was signed on September 28, 1931 and it was not until November 6 of that year that the Porsche firm presented its first design drawings to the board of directors at Zündapp. The issue of Motor-Kritik with the alledged photograph of Ferry Porsche and Adolf Rosenberger was published in early November 1931 - suggesting the photograph would have been taken most probably in the second half of October 1931, just as work was starting at the Porsche firm on the design for Zündapp.