Yes!! It is a Opel P4 by Stolle. And that results in the next point for you
As already mentioned, Opel changed the model designations from displacement volume to names in the mid-1930s (e.g. P4, Kadett...), certainly for German-speaking countries. In export, the displacement was still used in some cases, the Super 6, for example, was also called Opel 2.5. For the Puzzle vehicle, built in Hanover for a customer in Hanover, the designation "P4" was used in all probability. It is quite possible that vehicles of the same construction were also called "1.1 Litre" in the Expport.