I know that this last piece of information follows what is written on a plate at the Prototyp museum, but I think they mixed up the street Express (
http://www.autopuzzles.com/forum/index.php?topic=19214.0) and the railbound Express trains. There is a very detailed website about these two kind of trains which are closely connected. According to that site, the puzzle picture shows the so-called Hechtlok which began its duty on July 8, 1955 at the Berlin zoo. It was not commissioned by Henry Escher who was responsible for later versions, but by Arthur Franke. It is not clear yet, who built this Hechtlok, probably the same companies as for the later ones, i.e. Piotrowski for the bodywork amd Sollinger Hütte for the chassis. The Hechtlok was driven by a 1200 cc VW engine, and it carries the big VW logo at the front. Later versions for Henry Escher had Porsche engines and were known as the Porschebahn. Attached is a photo showing the opening of train service at the Berlin zoo.
