
Hi, we have a very active member here named A J and I am sure he will respond to your questions. If possible, post a few photos. You don't have to reveal where the car is, but the fourm members like to see the rare iron when possible. Good luck, Ed.

The only prewar "600" that comes to mind is the 1940 v12 prototypes. Registrations sometimes have odd model numbers as the owners could mistakenly put anything down. These days those documents have to be filled out with more precision.
Some pictures would probably clear the mystery up. MB had a dizzying array of models in the 1930s so it could be almost anything. A Vander Plas body would certainly be a rarity as there were few coachbuilt MB given the excellence of the factory offerings. Plus I don't know if I have ever seen a MB with a body from that particular coach builder.

One possibility I just thought of could be a mid-20s 630k which could certainly have a custom body.
I came across the photo of what is claimed to be a Vanden Plas body on a 540K. https://secure.flickr.com/photos/zappadong/7650718526/
The caption states, "Techno Classica Essen 2012 - Unique Vanden Plas body" so, being so recently displayed, you can probably find more info on this particular car or contact it's owners with a bit of research.
I went to the flickr photo, clicked on "original" size, and I could read the heading on the paper on the windshield. This car is for sale at Classic Motorcars Holland - Holten : Car details. Lots of info there. First owned by Randolph Hearst. The description does say Vanden Plas body.
