The key fobs of DAS (Drive Authorization System) equipped Mercedes contain a tiny RFID chip that is attached to the case of the FOB, not part of the circuitry inside. You can tell if your car has DAS by the circular transponder around the ignition which energizes and supplies the code from the chip to the DAS. I believe your 98 SLK is DAS equipped. If you need a replacement FOB you will have to get it from the dealer after supplying the VIN and proof of ownership. This is the only option to get the car started if you don't have the original FOB.
Of course this leads to the question: How did you manage to buy a car that wouldn't start?
Last edited by IndyBenz; 02-19-2010 at 11:21 PM.