I have had my 2012 ML 350 Bluetec without any issues for over a year near 20k miles. It has proven to be a tried/true work horse and I have no regrets. I have averaged an indicated 23 mpg during this period and on long Hwy seen about 29mpg driving a constant 80mph. Most of my commute is stop/go city w/limited fwy and it still gets 23-25 if you don't bury your foot to feel that strong 455ft lbs of torque.
I'm truly convinced that this is a great overall vehicle and am glad I chose this powertrain.
FYI think about it..for about $1500 extra at purchase it holds its value advantage of $5000-9000 or more than the gas engine over the same ownership period!
IMHO that is money in the bank .
Excellent MPG, Smooth and quiet Powertrian,Self-Automated Parking,Lane departure warning,Power tailgate,EZ blutooth connection and comfortable a/c seats.
None...I hope that all my ownership experiences will be as this one...the Longer I have owned it the more I truly appreciate it. It is a Great family vehicle!