The Good: The 2008 Mercedes-Benz ML550 combines sharp styling with even sharper performance, courtesy of its punchy 382-horsepower V-8. Its optional adaptive-damping system gives drivers the ability to optimize the ride based on driving environment. The Bad: As with many Mercedes-Benz models, the ML550's cabin tech lags behind that of the luxury competition. Its iPod interface is particularly bewildering. Fuel economy is disappointing for a car with such an advanced power train. The Bottom Line: The 2008 Mercedes-Benz ML550 is a brawny midsize SUV with some admirable on- and off-road performance capabilities. But its optional--and expensive--cabin technology lets it down. Mercedes-Benz engineers like to tell you that the company's philosophy involves starting with an engine and building a car around it. Based on the number of models that make use of the company's 5.5-liter V-8, we find it hard to disagree. Having reviewed the S550, the E550, the SL550, and the CL550, we were hardly surprised when the midsize ML SUV arrived at our garage furnished with the 382-horsepower flagship power plant. Like its stable mates, the ML550 also comes equipped with Benz's advanced seven-speed automatic transmission and some of the less-than-advanced cabin tech that we have come to associate with the current generation of Mercedes' base-level COMAND system. Test the tech: iPod integration Our Mercedes-Benz ML550 tester came with the unusual luxury of an optional iPod adapter. While we regularly note the availability of iPod adapters on new cars, they are usually dealer installs, so we don't get the chance to test them out in our review models (a rare exception being the 2008 Scion xB , which comes with an iPod adapter as standard). Mercedes promotes its $375 iPod integration kit with the claim that "taking your personal music collection with you wherever you go has never been easier." We had high hopes, therefore, when we plugged our iPod Nano into the ML550's glove-box mounted adapter. Our ML550 came with Mercedes' $375 iPod adapter.The first thing that we noticed after connecting our iPod was that, other than the appearance of the Mercedes tristar logo on the player's display, nothing happened. Our initial instinct was to look for some kind of virtual iPod interface on the car's in-dash LCD display, which would give us a means of navigating our iPod library using the COMAND system's hard buttons. Having searched in vain through the audio options, however, we reverted to the manual to find that the iPod is accessed by pressing the AUX button. Even then, there is no means of selecting tracks on the in-dash COMAND system display. Instead, all controls for the iPod are assigned to buttons on the steering wheel, with the multifunction instrument-panel display (nestled between the speedometer and the tach) providing text information on songs and artists. As we found in our review of the 2007 Mercedes-Benz E550, the instrument panel display on current-generation Benz models is often a far more useful system than the in-dash COMAND system. Nevertheless, the iPod interface is far from intuitive. With an iPod connected and AUX selected as a source, we had to press the steering wheel-mounted List button until the main iPod menu showed up on the white-on-black display. Using the up and down buttons on the left of the steering wheel, we could then cycle through the familiar top-level iPod category menu (songs, artists, albums, genres, shuffle, and so on) using the arrow buttons. To make a selection, we then had to use the Make Call telephone button on the right-hand side of the steering wheel. All iPod information is shown in the multifunction display in the instrument panel.We then had to revert back to arrow buttons on the left-hand side of the wheel to search with our chosen category, and then back to the right-hand side to make a selection using the phone button. When we went astray (as we did quite often), we had to use the Hang Up button (below the Make Call button) to back up one menu level. Not only did this interface take a long time to learn, it is arguably no safer than making selections on an iPod player itself, as it requires users to alternately use their left and right hands on the steering wheel to make selections. In the cabin The ML550 displays all of the cabin comfort you might expect from a Mercedes SUV. Our tester came with the optional $1,975 leather seating package as well as an attractive walnut-burl trim for the central stack and door trim, and a wood-and-leather trimmed steering wheel. We found the seats in the ML550 to be supportive to the point of being firm: having driven from San Francisco to Los Angeles and back over the course of the past three days, your correspondent still has a numb backside as of this writing. Our ML550 came with the $8,500 Premium III trim level, which gave it the familiar Mercedes COMAND interface with navigation comprising a small LCD screen set low in the dash and surrounded by black plastic buttons. As we found in our reviews of the GL450, the ML320, and the E320 Bluetec, the current-generation GPS navigation system from Mercedes-Benz comes up short in comparison to that of other premium automakers. Aside from its awkwardly low positioning, the COMAND display delivers blocky maps, which lack the crispness of many other systems on the market. Destination entry requires a fiddly joystick, which must be used to input letters one at a time. The joystick has the inclination to either tip over when attempting to make a letter selection or it fails to register a selection, requiring drivers to push it in multiple times. Programming the COMAND navigation system with the joystick can be frustrating.Any reader of CNET Car Tech will know by now of our many gripes with the COMAND system, so we'll spare you our litany of complaints. However, one incident with the navigation system merits a mention. On our way back from Los Angeles to San Francisco, we decided to use the ML550's points-of-interest (POI) database to search for a Mexican restaurant near Interstate 5 (we just couldn't face another lunch at Carl's Jr.). Having entered our restaurant request, we got a list of eateries that met our requirements, including a La Salsa restaurant in Los Banos, some 15 miles off the freeway. It was a considerable detour, we figured, but a worthwhile and well-deserved break from hours behind the wheel. With the destination set, we followed the turn-by-turn directions to find--to our considerable disappointment--that not only was there no Mexican restaurant at the destination, we were also in the middle of a residential estate, suggesting that there had never been a restaurant there in the first place. Hungry and dejected, we got back on the freeway and stopped at the next Carl's Jr. for a burger. The ML550's POI system was either wrong or out-of-date.One positive aspect of the COMAND system on long road trips is its support for a range of entertainment options. In addition to its optional iPod interface, our ML550 came with a LOGIC7 surround sound audio system with the ability to play MP3- and WMA-encoded discs via a single slot behind the navigation screen's motorized fold-down faceplate. With an MP3 disc playing, we could select between folders and songs by using the joystick, the hard buttons to the sides of the display, or the steering wheel-mounted buttons. Full ID3 tag information for digital audio files shows up on both the in-dash display and the multifunction display in front of the steering wheel. Those wanting to play more than one disc at a time will have to option up the $450 glove-box-mounted six-disc changer. Audio quality via the ML550's 440-watt Harman Kardon 11-speaker surround-sound system is crisp and clear with a strong bass note, courtesy of a separate subwoofer and a good acoustic range. When playing an MP3 disc, full track and artist information is displayed on the in-dash LCD display.Also part of the Premium III package, our car came optioned up with Sirius satellite radio, which, like the iPod interface, we found to be somewhat problematic to program. While it is easy to use the steering wheel arrow buttons to skip between songs within a certain category (such as new country, prime country, and outlaw country in the country category), it does not seem to be possible to change categories without digging down to the relevant menu using the dash-mounted COMAND module, and only then by pushing the joystick to the side while in the Sirius satellite radio screen. The other major entertainment option on our car was the $2,670 rear-seat entertainment system, which comprises two 7-inch seatback displays set into independent brackets to the rear of the front-seat headrests. The rear-seat system supports DVDs, CDs, and MP3s--inserted in a disc slot beneath the right-hand rear passenger's legs--and comes with two wireless headsets and a dedicated remote control. A cheaper option to keep the backseat passengers occupied is the $1,250 accessory rear-seat entertainment system, which comprises a single seven-inch display installed between the two front seats. Under the hood While the ML550 is more than 300 pounds heavier than the S550 and the CL550, the 382-horsepower all-aluminum V-8 still manages to endow it with breathtaking pick-up, particularly when using the Touch Shift controls mounted on the back of the steering wheel. Mercedes says that the ML550 will haul itself from standing to 60 in less than seven seconds--a claim that we were willing to believe after only a few seconds behind the wheel. Mercedes' 5.5-liter V-8 is used to power many of its most recent models.It may not be in the same performance league as the 2008 Porsche Cayenne Turbo , but the ML550 displays the throttle response and all-around driving dynamics that belie its ride height. And for those with deep-enough pockets, the midsize SUV can be decked out to look as fast as it drives with the addition of a number of external options, including the $4,640 20-inch AMG wheels with which our test car was equipped. Other performance notables on the ML550 include the Airmatic Semi-Active Air Suspension with Adaptive Damping System, which, in addition to automatically adjusting the suspension damping to the ride conditions, enables drivers to select one of three suspension settings: auto, comfort, and sport. Using a scientific, made-for-SUV testing methodology, we found there to be a significant difference between sport and comfort: in sport mode, we were unable to drink our (very full) cup of coffee without the drink spilling out over the cup every time we hit a bump in the road. In comfort mode, this problem was significantly reduced, and we managed to get through our double mochaccino without it going cold. Mercedes-Benz engineers will no doubt be happy to know that all those thousands of hours of R&D did not go to waste. Like all modern Mercedes SUVs, the ML550 comes with the 4Matic all-wheel drive system, which ensures a 50-50 split between the front and rear wheels. And for those few who want to take it off the road, a button on the central console recalibrates the traction system, brakes, and transmission for optimal schlepping. As part of the Premium III package, the ML550 gets the Airmatic Air Suspension with Adaptive Damping System.Despite having one of the most advanced drivetrains on the market, the ML550 delivered disappointing gas mileage: in our week with the car, we covered more than 800 miles in predominantly freeway driving, observing an average fuel economy of 17.7 mpg. This figure may be in line with the EPA's 2008 estimates of 13 mpg in the city and 18 mpg on the highway, but that knowledge did little to mitigate the $160 fuel bill for our trip to LA. In sum The 2008 Mercedes-Benz ML550 comes with a base price of $53,175, but a barrage of options packages will add significantly to the sticker price. Our fully loaded tester included the $8,500 Premium III package (DVD navigation system, rearview camera, Sirius Satellite Radio, Harman Kardon LOGIC7 audio system, Adaptive Damping System, air suspension, and a bunch of other creature comforts); $4,640 for the 20-inch AMG wheels; $2,670 for the rear-seat entertainment system; $1,975 for leather seats; $1,540 for black leather cabin trim; $1,110 for Keyless Go; and $375 for the iPod adapter. The grand total gave our car a final price of around $75,000. Other options can push the price of the ML550 above $80,000. With that kind of money to spend, SUV shoppers could also consider the 2007 BMW X5, the 2007 Infiniti FX45, or the 2007 Audi Q7. The Mercedes-Benz ML550 deserves the moniker of sport utility vehicle: its gutsy on-road performance and off-road credibility make it a versatile ride. It is let down, however, by some poorly integrated and expensive optional cabin technology and a less-than-economical fuel economy.