The Good: The 2006 Mercedes-Benz R350 combines the best features of a luxury sedan, an SUV, and a minivan to give its occupants an incredible amount of comfortable space. MP3-CD capability and a standard MP3\/iPod jack in the glove box will please contemporary music lovers, while the optional panoramic sunroof gives passengers a clear view above. The Bad: The 2006 Mercedes-Benz R350's V-6 is worked hard by the vehicle's size, and there is little cargo room with the car in six-place configuration. As with all Mercedes-Benzes, cell phone connectivity is limited to the manufacturer's own package. The Bottom Line: Mercedes-Benz is exploring new ground with the R-Class Grand Sports Tourer. With 4,800 pounds of heft, sport doesn't really apply to the 2006 R350, but with excellent passenger space and comfort, it's great for touring in grand style. Describing the Mercedes-Benz R-Class brings to mind the old fable of the blind men and the elephant. Like the elephant, the R350 is similar in detail to a number of other things; taken as a whole, however, it is very different from anything else on the road. The design of the R350 suggests that the German side of the DaimlerChrysler tag team seems to be learning new tricks from its American partner by creating new vehicular niches to keep ahead of its competition.The 2006 Mercedes-Benz R-Class combines the comforts of a luxury sedan with most of the space and versatility of a minivan or an SUV. While not as tall as the last two, it boasts more height than a sedan for excellent headroom. Legroom is also first class, and there is true space for six full-size adults in three two-seat rows. If the R350 is closest in concept to a tall luxury wagon, it doesn't fit the profile of a wagon or any other existing automotive genre.So what is the R-Class? Mercedes-Benz calls it a Grand Sports Tourer. If that sounds more than vaguely like Chrysler's Pacifica Sports Tourer, the two vehicles share no parts, and the R-Class is, well, more grand in design, social standing, specification, and price.In the United States, two models of the 2006 Mercedes-Benz R-Class are available: the R350, powered by a 3.5-liter, 268-horsepower V-6, and the R500, with a 5.0-liter, 302-horsepower V-8. Both have permanent all-wheel drive, the 7G-Tronic seven-speed automatic transmission, and the full array of Mercedes-Benz safety features. Interior tech features are led by an eight-speaker AM\/FM \/single-CD audio system with both MP3-CD capability and an input jack for an auxiliary audio player as standard. Options include the TeleAid telematics system, a GPS navigation system, a glove-box-mounted CD changer, Sirius Satellite Radio, and the Mercedes-Benz telephone system.Our 2006 Mercedes-Benz R350 test vehicle came with most of the key comfort options but few of the available entertainment packages. To the $48,000 base price and the $775 destination charge, add $690 for Obsidian Black paint; $900 for 10-spoke 18-inch wheels; $530 for the wood-and-leather multifunction steering wheel; $1,750 for the leather and burled-wood interior-trim upgrade; $50 for a rear cargo cover; $1,190 for heated front- and second-row seats; and $1,400 for the Airmatic air-suspension system. The $2,390 Panorama Roof package could be considered comfort or entertainment, while the $1,190 Harman Kardon Logic 7 audio system provides great sound. The $58,865 bottom line is not cheap for a Mercedes but will be hard to beat on a square-feet-per-dollar basis. Even the S-Class seems small inside in comparison.The 2006 Mercedes-Benz R350's sleek and different looks draw attention. "What is it?" is the most common onlooker comment. While the car's Mercedes-Benz heritage is obviously defined by the tristar, the low Mercedes sport grille, and lines that show similarity to several of the manufacturer's other current products, defining exactly what it is can be tricky. The R350's two-box shape is only superficially like a minivan's, proving lower and smaller on closer inspection, as well as lacking sliding doors. It is larger, with a more blended-in shape than that of an E-Class wagon, and it's definitely not an SUV.Our advice is not to try to categorize the R350. If you need space in a luxury vehicle, look here. All three seating rows are simultaneously usable by six-foot-tall adults. The power-adjustable first row is similar in design and dimension to that of the ML SUV--no complaints for space and comfort there--but the second-row seats are the best in the house. Although manually adjustable, they can be modified for fore-and-aft position and seat-back angle, and they give the chauffeured passenger the feeling of traveling in an executive jet.Second-row seats in the Mercedes-Benz R350 are the best in the house.Third rows are all too often temporary lodging for small children--but not in the 2006 Mercedes-Benz R350. There is more than adequate room for heads, legs, and hips for adults, and access is good, thanks to the spring-based mechanical-repositioning system used to easily move the second-row seats forward and automatically back. The car's third-row seat backs are individually adjustable, and each can fold flat. The same can be done with second-row seats for maximum cargo\/passenger versatility, although the R-Class is more likely to be used for passengers than cargo. Everyone gets cup holders and storage space.The only shortcoming with the R-Class interior is that luggage space behind the third row is limited. This will not be a problem for three couples out for the evening, but it can be an issue for six people on a week's vacation. Mercedes does offer help for this cargo-space deficit with a variety of roof racks and optional storage containers. In four-passenger configuration, no mere sedan will come close to the R-Class's combination of passenger and cargo space.The Panorama sunroof--at $2,390--is not cheap, but it does add serious upward vision for second- and third-row passengers. Made from smoked glass for UV protection, it runs nearly the whole length of the roof, and the front section can tilt or slide open. Unfortunately, because of the raked windshield, the front of the Panorama roof is too far back for front-passenger enjoyment. Power rear quarter windows are included with the sunroof for decent passive ventilation.The $1,750 interior-trim package in our test vehicle upgraded the interior to R-500 specs with full leather seating (instead of M-B Tex synthetic for the rear rows), burled-wood trim, and improved interior lighting. It gave a fine executive-boardroom ambiance.The $530 wood-and-leather multifunction steering wheel provided an upscale driver interface, with auxiliary controls for audio, information, and phone (if installed) systems. All main windows are power operated, as is the sunroof, and holding the SmartKey button can open them automatically on sunny days.Control of the 2006 Mercedes-Benz R350's audio system and optional navigation and phone systems is done through the latest version of the Mercedes Cockpit Management and Data (COMAND) interface. The climate system--dual-zone standard or optional triple zone (you can add separate rear controls)--is easily operated through its own set of self-explanatory controls. An interesting feature of the climate system is tunnel-closing mode, which automatically activates air recirculation.COMAND as implemented in the R350 is straightforward, with marked hard buttons for all systems to the left of the LCD and a numeric keypad for phone- and audio-system use on the right. A small joystick is used to move the cursor over onscreen soft buttons and to make choices from menus. Screen visibility is good, as it is positioned away from direct glare.The R350's telematics, communications, and optional navigation are controlled via the COMAND interface with an LCD in the dash. Without the optional navigation system, the COMAND system in our test vehicle controlled only the audio and information systems, and detailed study of the manual was not necessary for operation. The optional $1,190 Harmon Kardon Logic 7 audio system provided great quality sound with solid separation. Its six-CD changer is in the glove box, where the front passenger can easily reach it. Besides commercial and home-burned audio CDs, it plays MP3 CDs, displaying track, title, and folder information on the screen. Also hiding in the glove box is a minijack for an auxiliary music player, which will activate the same screen display. Sirius Satellite Radio is available, although it wasn't included in our test car.Without the optional nav system, the LCD shows a virtual compass, which picks up direction slowly and none too accurately.The standard dual-zone, automatic climate-control system works well, heating and cooling the 2006 Mercedes-Benz R350's cavernous interior relatively quickly. Control is thankfully not done through the COMAND system but by simple standard knobs.As with other Mercedes-Benzes, cell phone connectivity is limited to the Mercedes unit.Besides the navigation system and Sirius radio, the wide variety of factory and dealer-installed options available for--but not fitted to our example of--the R350 includes Parktronic; a power tailgate; rear side air bags; a rear-seat entertainment system with LCDs integrated into the back of the front headrests; bixenon headlights with curve and corner illumination; and an iPod docking system that includes steering-wheel-mounted controls and a visual display.With a 4,841-pound curb weight, true sport driving is not in the 2006 Mercedes-Benz R350's repertoire. Although the 3.5-liter V-6 is helped by the seven gear ratios of the 7G-Tronic automatic transmission, as well as the optional Airmatic air suspension with adaptive damping, two and a half tons does not make for sports-car-quick reflexes.Still, the R350 works well for its true intended purpose: touring at a quick pace. Here, both its drivetrain and suspension perform favorably, with nice acceleration, a comfortable ride, and very decent handling for a vehicle of its size.Power comes from Mercedes-Benz's newest 3.5-liter V-6, which has four valves per cylinder, as well as dual overhead camshaft heads instead of the previous three-valve, single overhead cam heads. The twin-cam design allows the phasing of each camshaft to be individually controlled for improved efficiency and power, along with lower emissions and fuel consumption. Electropneumatically driven, electronically controlled tumble flaps in each intake duct improve airflow and also help decrease fuel consumption and emissions. A balance shaft ensures the smooth operation expected from a luxury-vehicle engine.The R350's seven-speed V-6 engine has to work hard to shift the car's heavy frame around.The engine's maximum 268 horsepower (at 6,000rpm) and 258 pound-feet of torque (between 2,400rpm and 5,000rpm) are enhanced by the seven-speed automatic. The 2006 Mercedes-Benz R350 did well on both, with quick full-throttle acceleration (according to the manufacturer, a 0-to-60mph time of 8.1 seconds) and an observed fuel economy of just less than 20mpg in mostly highway and high-speed secondary road driving. EPA-mileage figures are 16mpg in the city and 21mpg on the highway.Like the ML-Class SUV, all R-Class models have the 7G-Tronic automatic transmission with the Direct Select column-mounted shifter for basic forward\/reverse\/park control, as well as rocker switches on the back of the steering-wheel spokes for manual shifting. This design frees up the console for extralarge cup holders--this is a vehicle made in the Alabama plant, mostly for the American market--and shifting gears with the rocker switches becomes second nature to operate after a little familiarization.Like other new Mercedes models, the R350 uses a column-mounted shifter to change gears.Nevertheless, due to the wide torque band and the transmission-control computer's ability to adapt shifting style to the driver's needs, shifting manually isn't vital. And the R350's character doesn't demand rough manual treatment, as it's more about relaxed cruising in comfort rather than frenetic speed.The 2006 Mercedes-Benz R350's suspension design is conventional and all independent, with double wishbones in front and a four-link system in the rear. The optional Airmatic suspension replaces the front coil springs and the rear air springs with pneumatic spring struts and active-shock damping from the active damping system (ADS). There are two driver-selectable ranges, Comfort and Sport, the latter of which interestingly is the default mode.We initially found that the R350 felt like a large, softly sprung luxury car. That was fine on the freeway and around town, but we were not looking forward to the back-road portion of the test. The Airmatic\/ADS-equipped R-Class did better than anticipated. The harder it was pushed, the firmer the suspension became, although never at the expense of comfort.Another feature of the Airmatic system is adjustable ride height. This feature automatically lowers the R350 at speeds of more than 70mph to decrease wind resistance and improve stability, and the car can be raised about an inch at low speeds for better clearance. The R350's aerodynamic design results in low levels of wind noise at all speeds.Full-time all-wheel drive, with a 50\/50 static front\/rear torque split, is standard, and the latest version of the Mercedes-Benz 4ETS traction-control system further improves traction by activating the brake on any wheel or when wheels lose traction, as determined by the ABS wheel sensors. In keeping with the R-Class's luxury-transportation mission, traction control is all-weather rather than performance based, and we noticed no lack of traction on wet roads.If it's a safety item or technology in a modern car, odds are it was invented by--or for--Mercedes-Benz. The R350 has the full complement of Mercedes active and passive safety features.The R350's unibody structure was designed and built to protect all occupants in the event of a crash. Repair costs for minor front or rear collisions can be reduced because of use of crash boxes, which are bolted rather than welded in place. Further protection comes from front and rear crumple zones and a strong safety cage around the passenger cabin. All seating positions have three-point safety belts, and dual-stage front, front side, and full-length window air bags are standard.The 2006 Mercedes-Benz R350's brakes are four-wheel antilock discs, with electronic brake-force distribution and brake assist. An ESP electronic-stability system, which helps control excessive oversteer or understeer, is standard.Two optional systems not on our test car are noteworthy. Neck-Pro front head restraints can protect the driver and the front passenger in a rear-end collision by automatically moving the headrests forward and upward to better support the head and reduce the chance of whiplash. The Pre-Safe system links sensors from the ESP and brake-assist systems to detect a possible impending accident, then tightens the driver- and front-passenger seat belts in preparation. If the front-passenger seat has memory, the seat will be moved to a safer position and automatically returned if the crash doesn't occur. If the car is fitted with a sunroof, the roof will be closed if there is the chance of a rollover.The Mercedes new-vehicle warranty for materials and workmanship lasts 48 months\/50,000 miles and can be extended at extra cost. The extended warranty is transferable to the next owner if the car is sold before the end of the warranty period. The first scheduled maintenance is free of charge.As of this writing, the Mercedes-Benz R-Class has not been rated for crash safety by the federal government.