Originally Posted by M.B.DOC

The 1997 C-class did use a different key than any other year C-class.

The key transmits a signal info into the chrome ring around the ignition tumbler & that signal allows the car to start. MB calls that DAS (drivers authorization system).

You can purchase a wallet key that has that ability as well.

I wouldn't own one of those cars w/o having at least 2 keys with that signal ability!!