Mercedes-Benz GL550/ML550 - Newcomers - ML550

The ML550 replaces the ML500, with more subtle visual upgrades. Its exclusive features include all-season tires on 19-inch five-spoke AMG wheels, projector-beam foglights, AMG rear bumper, square dual-exhaust pipes, standardsunroof, and aluminum, rubber-studded runningboards.

As on the outgoing ML500, the 550 further distinguishes itself from the ML320 with a chrome grille instead of a black one. Mercedes says that, with the added equipment, the ML550 represents a 6.1-percent-better value than theML500.

Both ML and GL550 benefit from 382 horsepower and 391 pound-feet, the torque peaking from 2800 to 4800 rpm, with similar fuel economy to the 335-horsepower, 4.6-liter V-8 GL and defunct 306-horsepower, 5.0-liter 24-valve M-Class.This is a right-size engine for the GL. It offers strong, linear acceleration without the neck-snap of an AMG model, but also with no hesitation. It does our 2007 Sport/Utility of the Year proud.

The GL550 is much more firm and agile than any Escalade or Navigator, although the test-drive route included fairly smooth New England country roads. The 21s felt as if they could make the sport/utility just a bit too firm onrougher tarmac. Even so, this engine/trim package is just what the GL needs-a bit more presence and authoritative power, albeit with unimpressive fuel mileage. The smaller, tighter ML550 feels quick and downright spry with the newengine, while in a less-practical SUV package than the GL's. It takes a back-to-back drive to remind you that the ML is a much smaller SUV, sharing only the A-pillar and front doors as far as sheetmetal goes.

Mercedes has suffered deserved criticism for spreading its AMG line through too many models, and the ML63 is a prime example. The ML550 is all the hot rod the M-Class needs to be, and it's a good argument for paring down the AMG linejust a bit further.