I bought my E320 Cabriolet used, at 35,000 miles, from a MB dealer in Bethesda, Maryland. 2,000 miles later, the top pump failed; thank God the dealer replaced it free under warranty, it woulda cost about $4,000. Since then I've put 65,000 miles on the card and have had three problems I'd consider non-rountine:
1. Water Pump failed twice. Dealer replaced it at 50,000 then it failed again at 60,000. My local Cape Cod mechanic, who fixed it the second time, said the dealer had installed it improperly. I couldn't get the dealer to agree, even when I showed how them the parts had been screwed in wrong. Spent nearly $3000 altogether.

2. Electrical gremlins. Passenger-side seatbelt system has a mind of its own; I have to drive with the belt locked to keep it from operating. Combo-switch failed at 75K, no brights and erratic wipers. Warning light for burned-out bulb remains on despite replacement of all bulbs. When I step on the brake (without headlights on) the light inside the ashtray lights, go figure. Antenna mast system grounded out, and burned out alternator (in a snowstorm of course). Ignition fuse has popped 3 or 4 times, rain or shine. Became quite adept at hopping out and replacing the fuse while smiling at stalled traffic behind me.

4. Transmission. Originally, just annoying -- when cold, car didn't want to shift from first gear until revved high. Now, reverse is failing and there's leakage at the front pump seal; I've learned this is a common problem with the 722.369 tranny. I only wish the $3500 needed to overhaul it was equally so common.

Ah well, it's still a snappy car and a babe magnet.