Define expensive problems only found on gas versions.

Other than the engine , the gas and diesel versions are the same so don't expect the diesel version of a "car" to last longer and have fewer problems.

Spring mount rust isn't something that happens in an instant. Inspecting the affected area and containing rust will prevent that.

They don't get the best mileage and they just aren't as durable as most older models. We had one for several years. We bought ours in 2009 with about 60,000 miles on it for $10,000. Little things would regularly break about once a week until 90,000 miles or so and then it really started taking a nosedive. The engine needed new crank sensors every few months, and it started gradually smoking more and more until it was no longer drivable. Two sets of catalytic convertors, two sets of valve cover gaskets. The dye on the seats wore off to the point where they looked awful within a few months and it ate front lower control arm bushings like candy. Interior parts seemed to be made from paper and the rubberized coating on all the buttons turned to goo and looked terrible within a year. This car was such a disappointment, that I won't buy another Mercedes made after 1996 or so.

This car was very close to mint condition when we purchased it, and I maintained it to the highest possible standard. It was great to drive, lots of power and very comfortable, but it was not the most durable Mercedes, by miles.

plastic garbage

Wow lots of W210 hate going on here. The W210 has proven to be the most reliable MB I've dealt with (along with my W203). The E320 sedans are fast, quiet, comfortable, and will absorb miles like nothing. I love my E320 wagon. It has a bit of rust, but the interior has held up pretty well and the performance easily outpaces my 420SEL. I will admit the interior isn't quite as well made, but the car as a whole is just as good and seems to be much more reliable in my experience. (3 W210's in the family) Also way easier to work on!!