The Good: The 2007 Mercedes-Benz GL450 is a refined and luxurious family hauler with enough performance credentials to hold its own on the freeway and on the trail. The Bad: From its navigation interface to the integration of its audio and video features, the GL450's cabin tech integration leaves something to be desired for a car of this price. The Bottom Line: The 2007 GL450 is true to the Mercedes-Benz mission of performance and luxury; however, its plentiful cabin tech features are not as useful or usable as we would like. 2007 Mercedes-Benz GL450Photo gallery:2007 Mercedes-Benz GL450The 2007 Mercedes-Benz GL450 is about as much Teutonic luxosheetmetal (to use a compound German phrase) as you can get on four wheels. At more than 200 inches in length, the seven-seat SUV has plenty of room to transport five full-size passengers in comfort, and even some usable room left over for the kindergartners in the third row. The real surprise with the GL450 is how much performance technology Mercedes has packed into it. For a car that is likely never to leave the asphalt or attack anything more strenuous than a multistory parking lot, the 2007 Mercedes-Benz GL450 comes loaded with an array of standard and optional equipment, from an enhanced off-road package to an adaptive suspension that lowers the chassis for greater aerodynamics on the freeway. Inside, the GL450 boasts a typically Benzian cocktail of comfort with two parts luxury and one part tech. Test the tech: Getting loaded with wine Running our eye over the extensive spec sheet for the 2007 Mercedes-Benz GL450, we noticed among its many performance features that it came standard with load-leveling suspension, which, according to Mercedes, "automatically compensates for changes in passenger and load weight." Hmmm, we thought, that sounds like a challenge. We determined, therefore, to load up the GL450 with a substantial cargo to see if the practice matched the theory. The first consideration was what kind of payload we would use for the experiment. While we recently managed to get a pack of eight dogs into the back of the 2007 Honda CR-V, we thought that a repeat performance would hardly be becoming of our leather-and-walnut-trimmed behemoth Benz. We needed something that would fit with the GL450's character, something upscale, something that smacked of the good life. What more worthy cargo, we resolved, than a load of wine cases? A phone call and a short drive later, we found ourselves parked outside Arlequin wine merchants in San Francisco's trendy Hayes Valley. Our plan was to measure the distance from the top of the wheel arch to the center of the Mercedes Tri-Star in the middle of the wheel, load the car up, and then take the same measurement with the car fully laden. If the load-leveling Airmatic suspension was worth its salt, the distance should be the same with the car empty as with the back stacked with Chateauneuf-du-Pape. With the car empty, the distance measured 18.4 inches. Having opened the car's automatic rear lift gate with nothing more than a push of a button on the key fob, we proceeded to load the GL450 to the roof with some choice vintages graciously selected for us by the store's manager, Chris. We packed the back of the GL450 with $7,500 worth of wine.The GL450's automatic third-row seats tumble forward and fold flat with the press of a button on either side of the cargo area. With the third-row seats stowed, the GL450 has 44 cubic feet of cargo room. Unfortunately, there is no automated system for loading wine into the back, and so it was by the sweat of our brow that we packed the car with 21 crates of wine of varying sizes. With the back fully laden, we unsheathed the tape measure once more. Although we didn't notice any self-adjustment going on, the GL450's load-leveling suspension worked as advertised: loaded with around 800 pounds, the distance from wheel arch to Tri-Star center point came in at 18.5 inches, suggesting that the suspension had indeed corrected itself to accommodate the load. The load-leveling suspension does its job well.In the cabin The cabin of the 2007 Mercedes-Benz GL450 is a refined, elevated perch from which to look down at other road users. A stitched, upholstered upper dashboard bedecked in Mercedes-Benz Tex is complemented by plush leather seats and burl walnut trim lining the dash, center console, and door panels. Our tester also came with an optional $540 wood- and leather-trimmed steering wheel to complete the luxurious ensemble. As we have seen on other Mercedes models, the luxury credentials of the GL450's cabin outweigh its technology offerings. Sure, the Benz cabin ticks all the boxes with its DVD-based navigation, hands-free calling interface, and MP3 and WMA digital-audio capabilities, but Mercedes is just not on a par with other (Japanese) automakers when it comes to bringing its interiors into the digital age. Let's start with navigation: As we found in the reviews of the 2007 Mercedes E550 and the 2007 Mercedes E320 BlueTec, the Comand screen is small and less-than-intuitive to use. Programming the system is less frustrating in the GL450 than in the E-class sedans, thanks to the presence of a joystick to the right of the display as well as a quicker processor that eliminates the lag between inputs. The voice guidance on the 2007 Mercedes GL450 is also more bearable than that in the previous Mercedes navigation system, as it actually sounds like a person rather than a machine. However, the navigation maps are still unattractive and uninformative; even at the maximum level of zoom, street names are not visible for many roads. The GL450's navigation system also lacks the text-to-voice technology that we have come to expect in high-end models, although the monochrome multifunction display in the instrument panel does give a reading of the current street name, which goes some way toward mollifying us. The GL450's maps are colorful, but they lack detailed information on road names.The GL450's audio system is a similar mix of decent technology with an unhelpful interface. Though the eight-speaker Harman Kardon audio system fills the cabin with rich acoustic output, drivers of the navigation-enabled GL450 will have to reach across to the glove box to get at the six-disc CD cartridge if they want to play disc-based music, and those who opt for the rear-seat entertainment system will have to forgo the generic auxiliary input jack for playing their iPods. While we're on the subject of the rear-seat entertainment system, the movie-watching experience suffers from a similarly goofy design. The DVD console is located beneath the right second-row passenger's seat, and it is almost impossible to see where to insert a disc without performing some kind of yoga maneuver. Other than the placement of the DVD slot, the dual rear-seat entertainment system is impressive; it's one of the few that we have seen that offers headrest-mounted screens (two pairs of wired headphones and a remote control are also included with the $2,650 option). On the positive side, the GL450's stereo can be used to play various kinds of digital audio, including MP3 and WMA discs. With such compressed audio formats playing, the LCD in the center of the dash displays information for the current track playing, but there doesn't appear to be any way to call up all the ID3 tag information associated with a specific disc (such as artist, folder, album, and so on). Our 2007 Mercedes-Benz GL450 test car came with the $4,500 Premium I option package, which equipped it with a power tailgate, a Parktronic radar-based parking aid, a DVD navigation system, autodimming\/power-folding mirrors, power steering, a memory system for the front seats, and a six-month Sirius Satellite Radio subscription. Parktronic is a very useful feature in a car of this size, and we especially like the cowl- and rear-deck-mounted LED clusters, which gives a visual indication of how near the car's front two front fenders and rear bumper are to obstacles: as proximity to an obstacle decreases, more lights illuminate, with the sixth and seventh red lights accompanied by a warning beep. The optional rearview camera ($500) was also handy in helping us get in and out of tight spots. Other impressive standard safety equipment on the 2007 Mercedes-Benz GL450 includes second-row seat-mounted air bags, window curtain air bags for all three rows, and active front head restraints. Additional options on our test car included a tri-zone climate control system ($1,320), which adds a rear climate zone and six extra vents around the cabin, as well as a glass sunroof package ($1,500), which includes a glass sunroof and power-rear three-quarter windows. We like the headrest-mounted rear LCD screens for the optional rear-seat entertainment package.Like the E550 and the S550, the Mercedes-Benz GL450 does come with the option of hands-free calling. However, those who want to connect their phones by the standard Bluetooth hands-free profile (rather than via Mercedes' proprietary MHI interface) have to fork out $408 for the pleasure of a separate module, another black mark against the GL450's cabin tech. Under the hood Before we go under the hood, the Mercedes Benz GL450's hood itself gives some indication as to its performance aspirations. With a power bulge and two air vents identical to those on the SL550, the mammoth SUV seems to wish it had been born as something toward the sportier end of the Mercedes lineup. With its 335-horsepower 4.6-liter V-8 engine, adaptive suspension, and steering-wheel-mounted paddle shifters, the GL450 does have the soul of a sports car, but that is somewhat dampened by its 5,249-pound curb weight. Nevertheless, this is one permanent four-wheel drive SUV that can pull its own weight: with the gears held into higher rev bands in manual-shift mode, the GL450 barrels forward with the swiftness of a much smaller car. In addition to its load-leveling capabilities, the air suspension can be configured in a number of ways to accommodate different terrains and driving styles. Our test car came equipped with the $2,200 off-road package, which endowed it with an Adaptive Damping System (ADS), enabling drivers to adjust the ride height of the vehicle using a rotary dial in the central column to accommodate a variety of driving speeds: Off-road 3 mode raises the vehicle's body a full 4.3 inches from its default (highway) height and can only be used up to a maximum speed of 20mph. Three other settings include Off-road 2 (body raised 3.1 inches, max speed 40mph); Off-road 1 (body raised 1.2 inches, max speed 60mph); and High-speed (body lowered 0.6 inch). The ADS will lower the car itself when highway speeds are reached. Also part of the off-road package, the GL450 also comes with two locking differentials for those who really want to maculate their $70K Benz through mud, water, or deep snow. The 2007 Mercedes-Benz GL450 comes with an impressive range of performance technology, including the Adaptive Damping System.Another standard performance feature on the GL450 is its adjustable suspension, which, in addition to the default suspension configuration, gives drivers the option of setting the suspension to Sport or Comfort mode. Driving around town, we noticed a demonstrable difference between the two settings: In Sport mode the tuning is surprisingly stiff with imperfections and bumps in the road translating into the cabin, and a more surefooted feeling in cornering. In Comfort mode--far more suited to the GL450's luxobarge persona--rough pavement is effectively damped out, leading to a very soft, lolloping ride. Other notable performance features of the Mercedes-Benz GL450 include its Downhill Speed Regulator (DSR), which can be set at speeds of up to 10mph to prevent the car running away on inclines; and a hill-start assist, which holds the car stationary for a few seconds to allow drivers to get their loafer from the brake to the gas pedal. Like the 2007 Mercedes S550, the GL450 does come with the option of Distronic adaptive cruise control, which allows drivers to set a constant distance between the front of the car and the back of the car ahead when driving on the freeway; however, our tester was not so equipped. In our week with the GL450, we observed an average gas mileage of 15.3mpg, right in the middle of the EPA estimates of 14mpg city and 18mpg highway, but disappointing for any new car, especially one with a seven-speed automatic gearbox. In sum The 2007 Mercedes-Benz GL450 comes at a base price of $54,900, but the price tag for our tester was supplemented by a litany of options: $4,500 for the Premium I package (DVD navigation system, Sirius Satellite Radio, Parktronic, auto-dimming power-folding mirrors, power steering, and a memory system for the front seats); $2,650 for the rear-seat entertainment system; $2,200 for the enhanced off-road package (Adaptive Damping System, two locking differentials); $1,500 for the sunroof; $1,500 for macadamia leather appointments; $1,320 for the tri-zone climate control; $900 for the lighting package (curve-illuminating Bi-xenon headlights, front fog lights); $700 for a Desert Silver paint job; $540 for the wood-and-leather steering wheel; $500 for the rearview camera; and $150 for ambient interior lighting. Oh, and don't forget the $775 destination charge. All told, our tester carried a hefty price tag of $72,135. At that price, the Mercedes-Benz GL450 is up against the 2007 Audi Q7, the newly remodeled 2008 BMW X5, and probably Lexus' forthcoming LX 570, to be unveiled at this year's New York auto show.