Mercedes-Benz GL-Class Performance
The 2008 Mercedes-Benz GL-Class is a superbly performing SUV, and earns a very good score and high performance ranking within the class. A powerful, but silent, V8 engine powers a car that Motor Trend says "never feels like a full-size brute that can swallow seven; rather, it drives small, coming across more as an S-Class sedan than an Escalade competitor."
This luxury SUV provides an excellent driving experience, with nearly every review noting, as New Car Test Drive does, that "the Mercedes-Benz GL 450 is large and capable off road yet feels surprisingly car-like on the road." This is in large part thanks to its unibody construction, instead of the body-on-frame construction that is typically used in most large SUVs and trucks. Edmunds notes the GL "manages to present itself with a touch of class. Its mechanical sophistication, unit-body construction and superior craftsmanship also set it apart from other seven-passenger full-sizers"
Ride comfort, as befits a luxury SUV, also puts the 2008 Mercedes-Benz GL-Class at the top of its class, thanks to standard all-wheel drive, an independent rear suspension, and features such as electronic stability control. AutoWeek adds that the GL550 offers "an impressive combination of power, smoothness, surefooted handling and luxury."
As previously noted, the 2007 GL-Class was recognized with several awards, including Edmunds' "Most Wanted SUV of 2007."
Acceleration and Power
The 2008 Mercedes-Benz GL-Class has three available engines. The base GL450 is powered by a 4.6-liter, 335-horsepower V8. The GL320 CDI is powered by a 3.0-liter turbodiesel V6 engine that makes 215 horsepower. The GL550, new for 2008, gets a powerful 5.5-liter V8 that makes 382 horsepower and 391 pound-feet of torque.
Motor Trend's tests showed the GL450 to be capable of getting from 0-60 in 6.7 seconds, the third-quickest time among the SUVs it tested, while Mercedes estimates the 0 to 60 time at 7.4 seconds. The standard engine is less powerful than the Cadillac Escalade, but Edmunds says that they were "impressed by the GL450's powerful 4.6-liter V8, which delivered quick acceleration times that bettered the competition."
Edmunds says the GL320 CDI, is the "most intriguing model in the GL-Class line" and that "like other diesel-powered vehicles, provides massive low-end response and superior fuel mileage versus its gasoline counterparts." AutoWeek notes that while the "diesel GL320 CDI isn't going to break any acceleration records, passing and merging maneuvers come easily" and add that the V6 "is so quiet and refined you're scarcely aware it's actually a diesel."
Motor Trend says the GL 550's 5.5 liter V8 is the "right-size engine for the GL. It offers strong, linear acceleration without the neck-snap of an AMG model, but also with no hesitation." The says the GL550's V8 engine is enough to launch the SUV "to 60 miles an hour in six seconds, more or less, despite weights of 5,434 pounds (GL)." However, the same review notes, "That sort of performance does not come without penalties," and calls the GL550 and its ML550 engine-mate "unabashed gas guzzlers." Motor Trend agrees that the 550 offers "a bit more presence and authoritative power, albeit with unimpressive fuel mileage."
According to the Environmental Protection Agency, the GL550 is expected to net 13 miles per gallon in the city and 17 mpg on the highway. The GL450 trim provides 13/18 city/highway. But buyers hoping to lessen any guilt over buying such a vehicle might consider opting for the diesel-powered GL320 CDI, which provides much better mileage -- 18/24 mpg city/highway. As Car and Driver says, "there are almost no downsides to the diesel," though one can expect getting to 60 in about 9 seconds, instead of the GL450's 6.7 seconds.
A seven-speed automatic transmission provides very smooth acceleration in all models, according to most reviewers. Edmunds says "the seven-speed automatic transmission does an exemplary job of keeping the engine in the meat of its power band." The Boston Globe reports that the transmission is "smooth as silk" and "has Mercedes leading the pack." For drivers who may need manual shifting for off-road conditions, the 2008 Mercedes-Benz GL-Class also provides controls on the steering wheel. Autobytel adds to the praise, saying "the seven-speed automatic transmission shifts sublimely under all circumstances, kicking down into the thick of the power with just a moment's hesitation." According to Mercedes-Benz, the transmission is also "intelligent": a computer program analyzes the driver's style and adjusts shift-points accordingly. AutoWeek says the system offers "smooth-flowing torque on command."
The GL Class has a maximum towing capacity of 7,500 pounds. Though few test drivers used the GL as a tow vehicle, Car and Driver reports, "We towed a little bit with our test vehicle, and we can say that it tugged like a champ, although we admittedly didn't really get anywhere near its 7500-pound limit."
Handling and Braking
Most reviews say that the 2008 Mercedes GL-Class offers above-average handling, despite the lack of road feel. AutoWeek says that all GL models "drive smaller than they are; agile handlers, they hustle quickly through curves." However, Edmunds says some "might find the Mercedes GL's handling to be a bit wallowy -- this isn't a truck you toss around for the sheer joy of it. But the ride and handling compromise is acceptable, and the GL's steering, although a bit slow, is nicely weighted and never numb." Car and Driver says the steering "feels as if road feel were being delivered to you on a tiny pillow by a tiny butler - but there is good precision and heft to the wheel."
The GL450 uses an independent rear suspension system for both the front and rear wheels as well as a four-wheel air suspension system which automatically adjusts for road conditions, and which can also manually raise or lower the car's chassis for those venturing off-road. Reviews say this suspension system does a very good job at providing a comfortable ride. Motor Week says " ride quality is way above average," while Edmunds warns that it "may be floaty for some."
Braking is provided by vented disc brakes, which are supplemented by a four-wheel traction system, which monitors the speed of all wheels for slip, and applies brakes individually as needed. Anti-lock brakes are standard. Motor Trend says that in its tests of SUV braking performance, the GL "finished near the front of the pack, tying with the much lighter Honda CR-V and Hyundai Santa Fe," going from 60 to 0 MPH in 129 feet. Car and Driver reports that their test GL "achieved a 70-to-0-mph stopping distance of 165 feet. Kind of pedestrian for a sports car, but when you consider that it took the last Lotus Elise we tested just three fewer feet to achieve the same, uh, feat, you kind of start to look at the GL550 in a whole new light."
Since the Mercedes all-wheel-drive system offers no low-range gearing, drivers seriously considering taking their Mercedes off-road might want to consider adding the off-road package, which adds an "Adaptive Damping System," allowing the driver to take more control over the suspension. This option allows the driver to choose between three-modes, Sport, Comfort, and Auto. AutoWeek says "though the big Benz is capable with the standard suspension, anyone who values body control and tautness in handling would be advised to opt for the adjustable suspension."