The 2006 M-Class that will be getting released in the Spring will have two diesel engine choices:

ML320 CDI: 221HP and 376 ft-lbs of torque
ML270 CDI: 184HP and 325 ft-lbs of torque

If you have enough money to buy brand new(or lease), just wait for the releases.

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver