Follow-Up Test: 2007 Mercedes-Benz ML63 AMG

We'd just finished displaying the awesome pulling power of the new 2007 Mercedes-Benz ML63 AMG, when one of our passengers, peeling himself off the back of his seat, exclaimed, "Oh, my god!"

Exactly, we said. In fact, don't think that AMG is an acronym that stands just for the founders, Hans Werner Aufrecht (A) and Eberhard Melcher (M), of Mercedes-Benz's in-house tuning and racing firm plus Aufrecht's birthplace of Grossaspach (G). AMG also stands for "Ach, mein gott," German for the expression exclaimed by our impressed passenger, and the words blurted out by almost everyone who drives one of the new-generation AMG vehicles powered by the company's awesome race-bred 6.2-liter engine.

We've said it ourselves, time and again, after driving the ML63's AMG-tweaked companions in the 2007 Mercedes-Benz lineup — CL63, CLK63, CLS63, E63, R63 and S63. AMG is nearly finished replacing its 5.5-liter supercharged engine with the more efficient, cleaner and more powerful 6.2-liter naturally aspirated V8; and the world is better for it.

Too much of a good thing?
However, even as we marveled at the ML63 AMG's performance numbers — zero to 60 in 4.7 seconds and a quarter-mile time of 13.3 seconds at 105.6 mph — we wondered whether there's any need for a sport-utility vehicle to attain such speeds. And then we realized that this line of thinking is a dead end. Heck, even AMG officials are quick to admit that no one really needs a 503-horsepower engine in an SUV. However, they're also quick to point out, with wicked grins, that everyone wants that kind of power. Point taken.

Besides, as AMG does with all of the vehicles it transforms into high-performance machines, an M-Class' conversion into an ML63 entails much more than just stuffing in that big engine. Brakes, air suspension, traction aids and running gear are all specifically tuned to handle the physical demands imposed on the chassis by the brawn of the sophisticated engine. All the tweaks provide a welcome balance to the prodigious power and make the ML63 almost as easy to drive quickly as one of AMG's sedans.

Eats Porsches for lunch
We knew the ML63 was going to do well in our testing, but the numbers it posted had us thinking there might have been a hiccup in the test gear's software. Nope; everything checked out: This puppy is quick. We were especially eager to see how it fared against the 520-hp $132,000 Porsche Cayenne Turbo S. Bottom line, it smoked the last Turbo S we tested by a half-second from zero to 60 and by almost 2 mph in the quarter-mile. The big Merc also bested the times we achieved with the 420-hp Jeep SRT8, arguably the only other sport-ute able to keep up with the powerful pair of Germans.

The ML63's speedy getaway comes courtesy of the V8's 465 pound-feet of torque and the instant response of the seven-speed automatic transmission, which conducts its upshifts so smoothly and quickly that the speedometer has to be consulted often to avoid cruising around at super-extralegal speeds without knowing it. The three-mode transmission can be operated manually with buttons on the backside of the steering wheel, but it's best to leave it in full automatic. Crisper shifts are available in Sport mode, but there's little gain to be made from using it unless an inviting road opens up before you.

Which should happen often, as there's little point to buying the ML63 just to muddle around town. There are more clever ways to spend almost $90 grand if the most rewarding element of the vehicle isn't enjoyed often. When the ML63 is unleashed on a curving road, the 10-way adjustable dynamic sport seats become your best friend, hugging you tightly and reassuring you with a stable point of reference to the chassis' pitching and yawing — what little there is of it.

Covered in napa leather (admire the stitching) with Alcantara inserts, the multicontour front seats are just one of the special AMG touches that contribute to every mile of driving enjoyment. We could do without the running boards, which only get in the way when climbing in or out, or the illuminated entrance plates, which seem an extravagance even in an extravagant vehicle, but we loved the exquisite workmanship and striking graphics of the AMG steering wheel and gauge package. What, though, does the ML63 need with a Lap Timer Function? Nürburgring, anyone?

The only downside to all the enjoyment is poor fuel mileage. The window sticker says 12 city/16 highway, but in one urban loop we got just over 10 mpg, even when driving with a lighter foot than normal. We shudder to think about a German ML63 owner having to pay more than $6 a gallon at every fill-up.

High and heavy
The all-wheel-drive ML63's heft not only adds to the fuel bill, it also makes the car want to go straight when the front wheels ask it to turn. This understeer, though mild, prevented the Mercedes from being as adept on the skid pad or slalom course as the Porsche, but the Cayenne sets a very high bar, and in that light the ML63 performed extremely well. The Merc pulled 0.82g on the skid pad compared to the Porsche's 0.85g, but neither of those two got close to the 0.90 recorded by the Jeep SRT8. Slalom times were close enough between the ML63 and Cayenne as to be equally quick, both carving the cones at speeds around 65 mph.

Our test driver, who finds traction aids to be nothing more than impediments to tail-out frolics, disliked the fact that the ML63's ESP traction system couldn't be totally disabled. In his view, this made his slalom runs a bit less fun, and efficient, than they could have been. We, on the other hand, can't imagine driving the ML63 without electronic aids. It's just too big and too fast to be flinging around like it's a sports car, even though it has the huge, sophisticated brakes of a sports car. Stopping distances from 60 mph averaged an incredible 114 feet, with no sign of fade despite repeated tests. It's a great result but still not quite a match for the Porsche's brakes, which stopped the 500-pound heavier Turbo S in just 110 feet.

A stable chassis is a huge factor in great braking, and here the ML63 excels. The dual-adjustable suspension offers exceptional chassis control, though AMG's logarithms for the Sport and Comfort modes instead seem built around Stiff and Less Stiff. There's more road feel than some buyers of "luxury" SUVs might like, and the 20-inch low-profile running gear doesn't help much to soften the ride, but neither does the ML63 crash and bang over the rough stuff. It feels as though every rivet, bolt and fastener throughout the entire car has been optimized to greatest effect.

Tail-wagon competition
Which brings up the subject of a competitor to the ML63 — not too surprisingly, it comes from within the ranks of Mercedes itself, the E63 AMG station wagon. OK, it gives up 4Matic all-wheel drive, which isn't available in the AMG wagon, a few inches of ground clearance and the elevated driving position, but otherwise the lighter and shorter station wagon is a fair match to the sport-ute if your definitions of such a vehicle include sporty and useful. Examples: The E63 wagon is about 800 pounds lighter than the ML63, its 6.2-liter V8 is rated a bit higher at 507 hp and, with its second and third row of seats folded, the E63 wagon provides almost as much carrying capacity as does the ML with its passenger row folded.

Yeah, we know. Marketing research shows sport-ute buyers are different from wagon buyers, and rarely does the twain meet. However, unless deep mud and snow, or a stream crossing, are common hazards to driving in your area, the E63 wagon, with its plethora of electronic aids, is capable of handling almost all marginal road conditions. The wagon is also arguably a safer place to be in the event of an accident, as the E-Class includes the advanced PreSafe system that prepares the car and its occupants for an impending collision. The E63 is safer, too, in a dynamic sense, with its lower center of gravity and sharper handling.

A $90 grand bargain
Fully laden with every option, the ML63 would cost somewhere on the upside of $90,000, extreme for sure, but still about $40 grand short of the Porsche Cayenne Turbo S. In Porsche's defense, the Cayenne does offer an array of options that provides exceptional off-road performance in addition to its blinding speed.

If your idea of a good time is to play Paris-to-Dakar on the weekends, the Cayenne might be worth the extra bucks. Otherwise, get the ML63 and put the saved money to a good cause, like a down payment on a Porsche Cayman S.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.