It’s a bit difficult to arrive at a definite conclusion, but although DKW was part of Auto Union their cars were not badged as AU until some time in the late 1950s, being known only as DKW despite both names being mentioned on their badges. But to call this car an Auto Union is a bit like calling a Mercedes a Daimler because it was made by Daimler-Benz AG..
I did say in an earlier reply that it was only “almost an Auto Union”, and that remains true. So this car is a DKW FX, which has been partly answered by del78 (who I’m sure who have reached the FX conclusion too if I’d had the chance to lock it for him) and partly by Thorax, who got the FX bit but repeated the erroneous Auto Union name.
So after consideration I’ve decided to give 1 point each to del78 and to Thorax, since I can’t give them half a point each!
I know at least 1 site that calls the car what mekubb wrote but it isn’t strictly true and both the DKW and the FX had been mentioned by the others already. However, he provided a date which the others did not and which I asked for in the original question, so I’ll be very generous and give him a point as well. That should mean everyone gets some reward for their input!