That's the one. This is the first in a series of amphibious vehicles constructed by Karl Baier of West Berlin sometime around 1950. Newspaper reports say it was powered by a 125cc engine giving 100mpg. A second version the "Familien-Freizeit-Auto" (Family-friendly car) appeared in 1953, this time powered by an air-cooled, rear-mounted 200cc two-stroke engine. The third and final version the "Wannsee-Auto" appeared in 1967. Mr Baier took out a few patents relating to his craft, but otherwise doesn't appear to have made much more of a splash.
http://trove.nla.gov.au/ndp/del/article/96398185?I don't have a copy myself, but I'm told that more details of Mr Baier's exploits plus information about one or two other micro-amphibians can be found in the German book
Mit dem Auto baden gehen by Rene Pohl and Rüdiger Haack. You can see (very small) photos of these and a few details of each craft on Rene Pohl's website
http://www.schwimmauto.de/
