This one is not based on a VW, but there was a 2nd prototype which was built on a Beetle chassis.
I just came across the second car, the 1969 Yak. It shared the same basic body, of course without the front engine bonnet. The two cars were developed by Kunststoffbüro Osnabrück Dr. Reuter GmbH + Co. KG, which was part of the Elastogran company, taken over by BASF in 1972.