Early Keyless-Go chip card (2003 cars)

The 2003 R230 could be optioned with an early Keyless-Go system that used a slim wallet 'chip card,' and owners note that surviving 2003 cars almost never still have that card, triggering a 'chip card not recognized' message when the start/stop button is pressed. The car otherwise operates normally on the standard fobs, and by 2005 the fobs alone activate the whole system.