Well, don't spread it around, but I don't think the 203 chassis has a security system on the radio. Don't feel too bad, cars with COMAND don't either, and that includes S-class and CL-class. Good luck trying to get a COMAND system to perform any useful function without being plugged into all the harnesses in back of it, but no, COMAND has no input for a radio code, either. I'll check this out a little at work, we have a few new C-class cars around. I know about the memory store functions of the new smartkey, but I sure would think they would have mentioned at the C-class technical introduction if the key has security info in it for the radio....Gilly