How reliable is the 5.5L motor? I'm considering purchasing one that has 50,000 miles for $26,000. Black on black and it is pretty well equipped (AMG, Harmon Kardon, etc). What do you guys think? Currently have a '12 E350 and it has been bulletproof.

Great and reliable motor but if you go with 2012 E550 you'll get more power with the twin-turbo V8 (also proven to be reliable) which also gets higher power increases with simple ECU tune. Can't go wrong with either motor but would suggest going with TTV8 as price difference is not huge with 1 model year apart.

Of the several Mercedes I have owned (including a new S550), my 2011 E550 is my favorite. Same ride as the S550 and same power. The engine in the 2011 has an outstanding history. If I were shopping for an E550 I would not consider the bi-turbo engine worth any extra money. Suggestion: you probably already know this but check the maintenance record of any used Mercedes before purchase.

Good luck.

Nothing beats a big naturally aspired German V8. Tons of torque, power without the stress and heat of turbos. Add to that great mileage (25mpg at 80mph on Hywy 5 between SF and LaLaLand - 24mpg at 90mph)

Wrap that engine around with the solid coupe body/suspension/interior (with the most comfortable seats/climate control, and you can cruise for hours without fatigue.