Used 2008 Mercedes-Benz R-Class Diesel

Optional V8 power is gone for the 2008 Mercedes-Benz R-Class, but this opulent oddball remains a competent and versatile vehicle, and it's cheaper than ever before to get behind the wheel.

The Mercedes-Benz R-Class has always been a vehicle without a clear identity. "Luxurious SUV-based minivan-ish wagon" doesn't have quite the same ring to it as Mercedes' moniker of choice -- "Sports Tourer" -- but that's as close as we can come to pinning down what the heck the R-Class is. Unfortunately for Mercedes, the R-Class, now entering its third year of production, has also turned out to be a vehicle without enough buyers. That should explain why Mercedes will hand you the keys to a 2008 model for about $42,000, down from about $48,000 in 2006.

As a further consequence of slow sales, the R500 and its robust V8 are no longer available. Nor, to the chagrin of deranged speed-freak socialites everywhere, is the R63 AMG, a 503-horsepower, physics-defying rocket sled that began and ended its stateside run in 2007. That leaves the R-Class lineup with two V6-equipped and hence not overly sporting "Sports Tourers" for 2008: the gas-powered R350, offered with either two-wheel drive or all-wheel drive, and the all-wheel drive-only R320 CDI turbodiesel.

Roughly 35 percent of R-Class components are shared with the M-Class SUV, its production-line partner at Mercedes' Tuscaloosa, Alabama, plant. Still, the 2008 Mercedes-Benz R-Class is very much its own vehicle. Of particular note is its prodigious length: At 203 inches from stem to stern, the R-Class is 3 inches longer than the rival Audi Q7, 8 inches longer than the similarly conceived Cadillac SRX and a foot longer than Mercedes' own E-Class station wagon.

The payoff is inside, where extraordinary spaciousness awaits. Third-row residents have rarely had it so good, as the R's roomy rearmost buckets pamper them in first-class fashion. The fore- and aft-adjustable second-row chairs are even more accommodating, though the newly optional seventh seat, which slots in between them, is only useful for quick trips. Lavish materials serve notice that this isn't your typical mommy-mobile. Less impressive, however, are the oversized conventional rear doors, which ostensibly facilitate third-row access but prove cumbersome in cozy parking spots. They're also heavy enough that small children might find closing them a challenge. Neither malady afflicts minivan buyers, who can enjoy power-operated sliding doors -- and probably every other option on the features list -- for considerably less coin.

But aping lowly minivans is hardly this Benz's raison d'être. Rather, it aims to provide carlike handling and SUV-grade versatility in a premium package capable of coddling six full-sized adults -- and in this narrow mission the R-Class largely succeeds. Indeed, it may be the only vehicle on the market that can cover all these bases. Sans V8 power, though, the 2008 Mercedes-Benz R-Class predictably has a harder time putting the "Sport" in "Sports Tourer." If this strikes you as a significant concern, and you can live with less generous third-row accommodations, swifter seven-passenger crossovers such as the Acura MDX, Cadillac SRX V8 or even Mercedes' own GL-Class may be more your speed.

The 2008 Mercedes-Benz R-Class is a large luxury crossover wagon with seating for six or seven passengers. Three trim levels are available for 2008: the two-wheel-drive R350, the all-wheel-drive R350 4Matic and the all-wheel-drive R320 CDI. Note that the 2008 R320 CDI will not be sold in California or states that have adopted California's emission standards.

Standard equipment on the R350 includes 18-inch wheels, leatherette premium vinyl upholstery, Mercedes' COMAND driver interface, bird's eye maple accents, a power driver seat, dual-zone automatic climate control and a single-CD stereo with eight speakers and a glovebox-mounted auxiliary audio jack.

Most desirable options are rolled into pricey packages, although a handful can be selected à la carte. Among the more notable add-ons are the new seventh seat, leather upholstery, burl walnut trim, an excellent 12-speaker Harman Kardon surround-sound audio system, satellite radio, park-assist sensors and a navigation system with a rearview camera. Other available accoutrements include a panoramic glass sunroof, 19- or 20-inch wheels, Bluetooth, keyless ignition, heated seats and steering wheel, a power rear liftgate, three-zone climate control, a rear-seat entertainment system, adaptive cruise control, and glovebox-mounted six-CD changer and dedicated iPod interface.

The big news under the hood for 2008 is what's missing -- namely, the now-defunct R500's 5.0-liter V8, not to mention the lunatic 6.2-liter V8 in the R63 AMG. Left to fend for themselves are a pair of eminently capable but relatively uninspiring power plants: the R350's 3.5-liter gas-swilling V6, which pumps out 268 hp and 258 pound-feet of torque, and the R320 CDI's 3.0-liter turbodiesel V6, which generates only 215 hp but compensates with a dump truck-worthy 398 lb-ft of torque.

The R-Class is still adequate in the performance department, as Mercedes projects 0-60-mph sprints of 8.0 seconds for the R350 4Matic and 8.6 seconds for the CDI. EPA-estimated fuel consumption is 15 mpg city and 19 highway for the 2008 R350 4Matic and 18/24 mpg for the R320 CDI. All models come with a seven-speed automatic transmission with manual shift control.

All R-Class models are outfitted with stability control with a rollover sensor, antilock disc brakes with brake assist, active front head restraints, side-impact airbags for front and second-row passengers, and side curtain airbags for all three rows.

The Mercedes R-Class hides its length reasonably well when you're at the helm, but you'll never mistake it for a traditional wagon unless said wagon transports caskets on a regular basis. We highly recommend the optional park-assist system for maneuvering this beast in tight quarters. That said, the R's steeply raked windshield affords excellent sight lines, and its substantial heft and autobahn breeding yield exemplary high-speed stability. Throw in appropriately subdued noise levels and a compliant ride, and you've got all the ingredients of a world-class long-distance cruiser.

Aggressive cornering is naturally not the R's forte, yet the four-wheel independent suspension and available Airmatic air suspension system admirably quell excess body motions. Still, if you're looking for a more responsive drive, there are several luxury crossovers available that are more involving.

The V6-powered R350 is acceptable in terms of acceleration, though the departed R500 was a full second quicker to 60 mph than the fleetest 2008 R-Class model, and its flexible power band addressed our central complaints about each V6 -- the diesel's breathless character at higher engine speeds and the 3.5-liter's lack of low-end grunt. Without the V8, the 2008 Mercedes-Benz R-Class no longer stands out from the luxury crossover crowd.

The interior of the 2008 Mercedes-Benz R-Class is both posh and functional. Gauges are large and easily read at a glance, most controls are ergonomically sound and appointments are generally befitting an upscale vehicle. All R-Class models seat six in rare comfort, and the R's combination of elongated rear doors and slick spring-loaded second-row chairs helps to facilitate third-row access. Moreover, with the second- and third-row seats folded forward, the R-Class can hold 85 cubic feet of cargo -- less than a minivan for sure, but on par with other luxury crossovers.

The new seventh-seat option, however, is a mixed bag. Wedged between the second-row buckets, the extra seat does add to the R-Class' versatility. But with noticeably firmer bolstering than the others, a seatback that encroaches on third-row knee room when in use and a too-narrow width for adult frames, it makes for a questionable addition.