Instrumented Test
For every market, there’s a sweet spot, a confluence of style and substance that resonates with buyers. That’s what Mercedes-Benz learned in 1997 when it debuted the original M-class. In the 15 years since, the competition caught on: The BMW X5 bowed in 1999, the Porsche Cayenne came in 2002, and Audi’s Q7, in 2005, and a slew of others now populate a mid-size-luxury-SUV segment that accounted for more than 125,000 units this year as of November. Within that market exists a small but vibrant subsegment of V-8–powered offerings. Mercedes has two eight-cylinder mid-size luxury SUVs: the ML550 and the ML63 AMG. These two combine to make up five percent of M-class sales nationwide. BMW’s X5 xDrive50i? Eight percent of X5 sales. And Audi no longer sells a vehicle in this segment with more than six cylinders. But those small numbers deliver a larger proportion of profits; Mercedes sets apart its two eight-pot MLs via price and performance.
Hot on the AMG’s Heels
The ML63 AMG’s fire-breathing 518-hp, 5.5-liter twin-turbo V-8 will launch the two-and-one-half-ton SUV to 60 mph in 4.2 seconds and through the quarter-mile in 12.6. But the ML550 is hot on its heels at 4.9 and 13.4 seconds, respectively, courtesy of its own twin-turbo V-8, this one displacing 4.7 liters and producing “just” 402 hp. The ML550 is what you might call AMG Lite. Sure, it has more than a little AMG flavoring, with AMG front and rear fascias, AMG five-spoke alloy wheels, larger-diameter four-wheel discs, a shorter 3.46:1 final drive, a paddle-shifted seven-speed automatic transmission, and 4MATIC permanent all-wheel drive. Nevertheless, the 550 has fuel economy and cost on its side. Working through a new transmission with a torque-converter-lockup clutch that now works in all gears—not just the top two cogs as previously—Benz’s size-medium SUV carries EPA-estimated fuel-economy numbers of 15 mpg in the city and 20 on the highway, easily besting the thirstier ML63’s 13/17 estimates. And even though the ML550 doesn’t carry all the $97,005 ML63’s luxury and performance fare, it starts out some $37,000 less expensive.
The 2012 ML550 we tested had a base price of $58,465 (2013 models start at $59,705). It came standard with Attention Assist driver-drowsiness detection (if it detects erratic steering, a coffee-cup icon illuminates and warning chimes sound), Pre-Safe (if a collision is likely, it snugs seatbelts, adjusts the seat, and can even close windows and the sunroof), mbrace (a GPS-based emergency-response, roadside-assistance, and concierge service), nine airbags, and luxury-car trappings such as a sliding-glass sunroof, power heated front seats, rain-sensing wipers, a leather-wrapped steering wheel, and a power liftgate.
To that, our ML550 added the Premium package, which included auto-dimming and power-folding mirrors, COMAND infotainment with navigation, a rearview camera, a memory function for the driver’s seat and steering wheel, a 14-speaker Harman/Kardon surround-sound audio system, and pushbutton start ($5370). The Dynamic Handling bundle was packed in, too, bringing active cruise control, adaptive damping with Comfort and Sport modes, an air suspension (it lowers the ride height at freeway speeds and can raise it three inches for off-pavement operation), Active Curve Control (with hydraulic actuators to reduce body roll during cornering), and 20-inch AMG-styled wheels ($5150). Other options: Dakota Brown paint ($720); Almond Beige leather ($1620); a heated steering wheel ($225); a trailer hitch ($550); and the Lane Tracking package that includes blind-spot and lane-keeping assists ($850).
