What exactly is the 2007 Mercedes-Benz R-Class? If you fall in step with Mercedes' marketing pitch, you'd be inclined to think it's a "sports tourer," a vehicle that busts market segment types by combining the best qualities of a car, SUV and minivan. People of a more skeptical nature might just declare, "Isn't it just an oversized station wagon?" No matter what you believe, however, there's no denying that the R-Class is an intriguing vehicle that represents a luxurious and powerful form of family transport.

The R-Class debuted last year as an all-new vehicle. Mercedes-Benz derived inspiration from its 2002 Vision GST ("Grand Sports Tourer") concept vehicle, and much of the R's underlying hardware is related to the current M-Class. When you first see it in person, you might be surprised by its size. The R-Class, which is available as the R350, the R500 and, as new additions for 2007, the R320 CDI and R63 AMG, is big. At 203 inches long, an R-Class extends past an E-Class wagon by a foot.

Fortunately, that size does translate into plenty of room inside. This Benz features three rows of two-passenger seating. The second-row captain's chairs are quite comfortable and even the third row is suitable for adults as long as trip durations are moderate. For access, there are two traditional rear doors. Though the doors open wide and avoid the minivan-like styling inherent in sliding rear doors, they are quite long and heavy. The former can pose a problem in tight parking lots, while small children seated in back can have difficultly dealing with the latter.

Still, the positives far outweigh the negatives for Mercedes' "sports tourer." It's roomy, stylish and can be packed with just about all of Benz's latest techno toys. It also comes standard with all-wheel drive to provide extra traction in times of inclement weather. For those wanting a versatile luxury vehicle that deftly sidesteps the perceived stigma of a minivan (or an SUV, for that matter), the 2007 Mercedes-Benz R-Class makes a lot of sense.

The 2007 Mercedes-Benz R-Class is a large luxury wagon that provides seating for six passengers. There are four trim levels available: R350, R320 CDI, R500 and R63 AMG. The R350 and R320 CDI are equipped similarly and come standard with 17-inch wheels, heated outside mirrors, rain-sensing wipers, dual-zone automatic climate control, real maple wood trim, a power driver seat, the COMAND interface and a CD player with an auxiliary input jack. Stepping up to the R500 provides 18-inch wheels and heated front seats. The flagship R63 AMG features special interior and exterior styling details, a sport-tuned air suspension, 20-inch wheels, stronger brakes, sport seats and much of the additional equipment detailed below as standard.

Options for the lower three trim levels are mostly grouped in large (and expensive) packages. Exterior or mechanical upgrades include a Panorama sunroof, power rear quarter windows, a power rear liftgate, park assist sensors, an adjustable air suspension, adaptive xenon HID headlights and an AMG Sport styling package with 19-inch wheels. Inside, you can further equip the R-Class with leather upholstery, rear seat heaters, a power passenger seat, driver-seat memory and tri-zone climate control. Satellite radio, a Harman Kardon surround-sound audio system, the TeleAid emergency call system, a navigation system with a rearview camera, a rear-seat entertainment system, adaptive cruise control and remote entry/start are also available.

Each trim level has a distinct engine. The R350 has a 3.5-liter V6 that develops 268 horsepower and 258 pound-feet of torque. The R320 CDI is diesel-powered. Its 3.0-liter turbocharged engine is capable of 215 hp and a stout 398 lb-ft of torque and, like most diesels, provides impressive fuel mileage (21/28 mpg) and range. Buyers should be aware, however, that the R320 CDI is not for sale in California, Maine, Massachusetts, New York or Vermont due to stricter diesel emissions standards.

The remaining trims come equipped with V8 engines. The 5.0-liter V8 in the R500 is capable of 302 hp and 339 lb-ft of torque. For the R63 AMG, Mercedes installs a monstrous 6.3-liter V8 that makes 503 hp and 465 lb-ft of torque. Mercedes says the R63 can hit 60 mph in 4.9 seconds -- as quick or quicker than a Porsche Cayman S. All models are fitted with a seven-speed automatic transmission and all-wheel drive.

With the standard suspension, body motion is adequately controlled, but opting for Mercedes' Airmatic air suspension system ensures just the right damping for all situations. This is no sports car, but for what it is, Mercedes engineers did themselves proud. The seven-speed transmission has a lot to do with the vehicle's impressive performance; although we think it could downshift a little quicker, it's geared perfectly and clicks off swift upshifts when the driver has his foot down. The 3.5-liter V6 lacks punch off the line but pulls respectably once up and running; the diesel V6 has the opposite problem, as it has plenty of grunt down low but gets a little breathless at highway speeds. The R500 is a solid (but pricier) compromise between the two, while the R63 AMG earns the top prize for "most demented" minivan.

The 2007 Mercedes-Benz R-Class wagon's interior is plush and smart in design. Gauges are well placed and controls are mostly intuitive. The vehicle comfortably seats six; even the two rearmost seats are pretty comfortable for adults. Mercedes has made third-row access easy by expanding the length of the rear doors and putting both second-row seats on spring-loaded hinges. They jump out of the way with the flick of a lever, and snap back into place just as easily. With the second- and third-row seats lowered, the R-Class can hold 85 cubic feet of cargo.