On our side of the pond, we had the W124 through 1995 with a metal key and a traditional key switch.

Starting in 1996 we got the W210.

First year 210s had the metal key and I believe it was still just a standard switch.
mid 1996 to 1997 added the RFID chip and the DAS (Drive Authorization System) to the metal key. Jeremy5848 has had firsthand experience with this on his early 96 W210, his car has the standard key only, and when the switch failed, they tried to sell him a DAS lock but his car was one of the original 210s with the standard switch.

1998 and newer changed to the bladeless key with RFID and DAS. This is what I have.

If the RFID chip in the key does not satsify the DAS, the steering will not unlock, the engine will not get any fuel (electric SOV will not open), the drive by wire electronic accelerator control will stay at idle position, and the transmission will not be allowed to operate. This happens over CAN bus so it is very difficult to defeat.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech