The engine options on these cars range from an I4 to a V8, with many V6 models in between.
These cars have been sold as coupes, sedans, convertibles, and even as station wagons. There's a reason these sell better than any other Mercedes model: there is an E-Class for anyone with enough money to spend.
The W210 was the first of the modern E-Class cars. It was only sold as a 4 door sedan or a 5 door station wagon. Engines ranged from an I6 to a V8, and were paired with a 5 speed automatic transmission. The W211 that would replace the W210 for the 2003 model year is seen by most experts as a huge improvement. The E550 and E63 AMG are especially well-liked by car buffs.
The W212 will replaced the W211 in 2009. No word yet on what improvements will be made on that car.
These cars sell in the $50,000 range, although the AMG variants often retail for $80,000 or more. You can buy them used for much less, but only if you know where to look. Some Mercedes dealers will carry the used cars, but others won't. You can always find some listed on eBay.