I only owned one, from new to ~119,000miles, and it was trouble. Part of the trouble was the M103 engine, part of it was the transfer-case seals, part was the heater blower and a couple of other accessories that wore out such as the orthopedic-seat controls which took out the $400 seat & locking pump.

People have told me that the transfer case will eventually leak internally, mine leaked externally, but still a "young" car when I sold it at 6years old.

I think that other than the transfer case seals, it is no more or less dependable than any other 300TE/300E M103 car, things wear out. The good news is that IMO the 4matic system is quite durable if fluids and all are kept in good condition, it doesn't seem to be vulnerable to spirited driving. Styre-Puch did a fairly industrial job of building the on-demand 4WD system.

The later W210-based 4matic systems are IMO more of a Japanese AWD variant and is reactive like the first system, but uses viscous-couplings and traction control to arrest wheelspin. Not my preference, took me back to permenently-engaged AWD of the quattros, Land Rovers, and Hummer H1 (excluding the TT quattro system).

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Gone to the dark side

- Jeff