M272's started going in to W211's as early as 2005.
Read about these engines here : Mercedes-Benz M272 engine
M273 engines had similar problems.
M271 4 cylinder engines had their own set off issues - similar to M272.

Although - AFAIK no 4 cylinder E classes were sold in the U.S.

W211's up until the 2006 update had issues with the fly by wire braking - steer clear unless you want to fork out $$$$$ for a new module.

Late 2007 cars onward are the ones to go for.

Dare I say it - as a W210 owner. W210's are now getting up in age. If you have one and have had it for a while - no big issue but I wouldn't be going out of my way to get one unless you find a really good one.

My W210 has just 100,000 miles on it and still drives like a Limo.
I was going to replace it with a late W211 but couldn't find one with the low mileage and reasonable price. So I bought a low mileage W204 C300. (25K miles). The W210 will be kept and used for the long journeys