Hallo Dietmar. It appears that site is for newer cars only. In the "fine print" it says cars from 1981 or newer. Our cars have a 14 digit VIN. Using the VIN, you can find out basic information such as the year your car was produced, which model it is, and whether it is manual or automatic. Of course, most of this you probably already know. This number is located in a couple places on the car. It can be found on the plate on the firewall, and also is stamped just under the venturi/intake manifold on the top of the subframe rail. Maybe more with the 280SL.
For further information about what options your car had, where it was first delivered, and much more, you need to obtain the car's data card. Search here for how this is done.
If you are trying to track down the vehicle's history (z.b. accidents, previous ownership ...) this can be difficult especially in California as the Department of Motor Vehicles keeps this confidential. Hope this helps you some.
James
63 230SL