Check the front upper spring perches, I have a parts car that the RF rusted through.

From what I've seen from others and what I've done to my 97 C280:

The torque converter clutch starts to drag, at minimum it gives a torsional vibration at light throttle in 4 and 5 th , at it's worst , it can stall the motor on a cold engagement.

The fuel tank senders ( 2 ) can fail. I took mine apart and cleaned the wiper. Ethanol fuel corrodes the copper.

Some have reported issues with slow filling of the tank, there is supposed to be an EVAP valve near the fill neck that sticks the won't let air out of the tank during filling.

Some have reported timing chain failures. It ends up being cheaper to just change the engine since engines in northern states outlive the bodies.

The C230 has manual knob type HVAC rather than the LCD "can get data out" type.

The dashes tend to lose pixles as the ribbon cable fractures. Cables are all over e bay. I have a sample dash I'm going to repair at some point.

The 4 cyl is kind of rough, especially after coming out of my 97 C280 inline 6.

Headliner cloth falls off.

The smart key can fail and is a bit of $ to fix. ( 97 was the last year for a metal key with a RFID chip )

The supercharged 4 has slightly less power than the inline 6 so no real gain there.