Want a real money-pit? Own a 1992 300SD. Now that's an early 140-series car with the "rod-bender" 3.5 liter diesel engine to boot!

I can't think of a more unreliable Mercedes model than the W140 diesel (at least the US-market car) off the top of my head. I know the 6.3 and 6.9 were quite expensive to keep up, but I wonder if they were on the level of a W140 car.

I assume the 600SEL must be a bear to maintain, due to the V-12 motor (no DIY to speak of) and every crazy W140 option being included on the thing.

-Sam