We could be here all day debating the logic of an ultra-high-performance sport utility vehicle. Even enthusiasts who love fast vehicles wonder why anyone would need a super-powerful SUV.
Listen: I don't build 'em. I just write about 'em. I've written about the 420-horsepower Jeep Grand Cherokee SRT-8 and the 450-horsepower Porsche Cayenne Turbo.
But now comes -- depending on your perspective -- perhaps the most compelling, or the most absurd, SUV of them all: the 2007 Mercedes-Benz ML63 AMG, with a 6.3-liter, 503-horsepower V-8 engine.
How Mercedes -- or more accurately, its in-house hot-rod shop, AMG -- accomplished this is pretty simple: It took a 6.3-liter V-8 used in other products, such as the E63 AMG station wagon or the CLS63 AMG sedan, and jammed it under the hood of Mercedes' Alabama-built M-Class sport ute, which was redesigned in 2005. The M-Class sport ute came with either a 3.5-liter, 268-horsepower V-6 or a 5.0-liter V-8 with 302 horsepower.
Mercedes-Benz added a beefed-up seven-speed automatic transmission, big P295/40ZR-20 performance tires on alloy wheels and a specially tuned suspension that make you forget the ML63 AMG weighs a whopping 5,093 pounds and is 73.3 inches tall. That suspension, plus every electronic bell and whistle you can imagine, lets the ML63 AMG corner like a sports car, but still, the ride is more than acceptably smooth.
And to make this whole proposition even stranger, Mercedes-Benz insists that the ML63 AMG can be taken off-road, though that thought never occurred to me. Specifications list a transmission that, when you drive off-road, adapts its shift patterns to your requirements. Performance listings include a "maximum low-speed water fording depth," but that depth is "to be determined," presumably waiting for a report from the first customer who tries it. But there just isn't much ground clearance, and there are a lot of expensive-looking aluminum suspension pieces under there, so let's just keep it on the pavement, OK?
Mercedes does, however, rate the ML63 AMG to tow 5,000 pounds, which isn't bad for a vehicle that, the company says, can go from 0 to 60 mph in 4.8 seconds.
Inside, the ML63 AMG has some of the nicest leather upholstery and burled walnut trim you have ever seen. Instruments and controls are typically means-business German, though they aren't hard to figure out. After all, this is a vehicle that was developed for an American market, and it shows in the nice cupholders, a big, illuminated two-tier glove box and zillion-watt Harmon-Kardon stereo with "digital surround-sound."
For what it is, I can't fault the ML63 AMG, except for its penchant to visit gas stations, 91-octane premium, please. The quality and fit is impeccable, and the performance astounding, especially because it is accomplished without turbochargers and superchargers. BMW used to be the dominant German premium manufacturer for high-performance vehicles, but man, these past few years AMG has tweaked most every Mercedes product into a roster of superb hot rods.
You already know it doesn't come cheap, right? With shipping, the ML63 AMG costs $86,275, about double the cost of the Jeep Grand Cherokee SRT-8, which isn't quite as fast, but is every bit as compelling -- or absurd.
Your call. Your money.
Base price: $85,500.
Price as tested: $86,275.
EPA rating: 12 mpg city, 16 mpg highway.
Details: Front-engine, all-wheel-drive SUV with a 6.3-liter, 503-horsepower V-8 engine and a seven-speed automatic transmission.