If it is not for a newish car , you can write to the Classic Centre in Fellbach , enclosing proof of ownership ( copy of registration document ) as required by German law .
They can provide this information from the archives , when I did this in the early 80's for my Ponton , I received back a very nice letter from Herr Von Pein and numerous documents including the requested information , data card , windscreen consignment sticker , factory photographs and more .
Nowadays , you can request a vehicle 'birth certificate' which is accepted by DVLA as proof of date of manufacture for registration purposes , although there is now a fee .
I had to verify my 1973 R107 about 6 years ago . The DVLA requested proof of build , so I contacted MB Customer Assistance in Maastricht. They sent me a letter on headed paper stating the approximate build date.They were unable to say where it had been sent from the factory , but the letter was sufficient for me to register the car. ( the previous owner had the car for 23 years on a personal plate , and re-registered the car before i bought it. Despite having a DVLA issued plate , when I applied for a registration document I had to take the car to Bristol VRO , and was advised the car was not correctly registered!).