I've had several w210s (3 wagons and a sedan) and haven't had major problems with any of them. Of the cars below, the 01 has about 150k miles and the 02 has 130k. The 02 is starting to show some rust (it was in NY state at one time). The 02 has a little rust under the rear window (common), but no other that I can see. It has spent most of its lfe in PA (where the road salt is bad, but not as bad as NY).

If the car you are looking at is from the south east, rust may not be much of an issue for awhile. Other than rust, my biggest concern would be transmission service. Its a big plus if has been serviced with proper fluid.

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126