By PETER PASSELL
Published: February 12, 2006

WHAT is longer than a Cadillac Escalade and heavier than a Honda Odyssey, yet handles as well as most contemporary German sedans? Oh, did I mention that the vehicle in question can carry a family of six in serious luxury?

The Mercedes-Benz R-Class isn't quite an S.U.V. or a minivan, and it fits into a niche that, until recently, didn't even exist. The advertising copy calls it a "sports tourer," a useless description that could just as well apply to an Aston Martin Vanquish. The closest existing match is DaimlerChrysler's own Pacifica, a long, tall wagon — or "crossover vehicle," in the industry vernacular — with pairs of seats in three rows. But while no one can claim with a straight face that the Pacifica is fun to drive, the R-Class can be surprisingly engaging.

Whatever you call it, the Alabama-built R-Class makes quite an impression on the street with its aggressive Mercedes nose and long swooping roof line. The curves give it a less macho look than the typical full-size S.U.V., yet it is easily distinguished from the dreary, box-o-cranky-kids look of a minivan. While not everybody takes to the styling at first, almost everyone agrees that it looks expensive.

And that's the rub: the R-Class is expensive. While the base V-6 model can be had for less than $50,000, it isn't hard to spend another $15,000 on a bigger engine and extras like an oversize sunroof, three-zone climate control, rear-seat entertainment and parking sensors.

While one might assume that the R-Class is just a fancy Pacifica, the two vehicles share little except a basic concept; rather, it is the new unit-body M-Class S.U.V. that played Adam to the R-Class's Eve.

Three trim levels are offered. The base R350 comes with a 3.5-liter V-6 that turns out 268 horsepower — and probably more important, a solid 258 pound-feet of torque at relatively low engine speeds. The R500's 5-liter V-8 generates 302 horsepower and 339 pound-feet. The R63 AMG is a new 503-horsepower speedwagon.

All versions come with full-time all-wheel drive and a seven-speed automatic transmission.

As expected with a vehicle this pricey, the base model comes nicely equipped with electronic traction and stability control systems, side-curtain air bags for all three rows, leather seats all around with eight-way power and memory settings up front, maple trim, power tilt-telescope steering wheel and rain-sensing wipers.

But there's plenty more to buy: the R500 I tested came with the aforementioned Panoramic sunroof ($2,390), Airmatic air suspension ($1,200), an iPod integration kit ($350) and key-free ignition ($1,080).

Outside, the R-Class could be taken for a postmodern hearse. Inside, you might think it was an exceptionally well-appointed minivan; even with the sunroof's shade drawn, the cabin had a greenhouse feel.

The front and second-row seats are firm but very comfortable, providing enough leg- and headroom for four-fifths of an N.B.A. team. The third row isn't in the same league, but offers tolerable space for two adults and room for groceries in a well behind them. The second and third rows fold flat, minivan-style, to create 85 cubic feet of room for hauling the proverbial kitchen sink.

The big surprise here is that, despite its bulk and weight (4,845 pounds), the R500 behaves like a luxury sedan tuned to the tastes of serious drivers. While 302 horsepower is modest by contemporary rocket-ship standards, the humongous vehicle scoots from zero to 60 in just 6.5 seconds, according to Car and Driver magazine. And with the sophisticated transmission willing to skip two or three gears as it downshifts, the R500 delivers great acceleration in the crucial 30 to 50 m.p.h. range.

The air suspension is soft enough to smooth harsh pavement (and spare the kidneys of third-row passengers atop the rear axle), but also smart enough to keep the R500 level in high-speed turns. The electronic stability control and all-wheel drive are up to the task of keeping aggressive pilots out of trouble without spoiling the fun. The steering has enough power assistance for easy handling in heavy traffic but retains road feel on the freeway.

All told, the R-Class is a pleasure to maneuver. In fact, it is the first really big vehicle I would happily drive in lieu of a peppy, well-mannered midsize sedan. The catch, alas, is that the R-Class is very costly to buy — and to fuel. I managed just 14 m.p.g. of premium gasoline in a mix of city and back-road driving, and a disappointing 20 m.p.g. while cruising the California freeways.

The obvious question is why anybody would pay $50,000-plus for an R-Class when all manner of nice people-haulers come for $20,000 less.

One reason is snob appeal — a Pacifica or Odyssey isn't dressed to impress valet attendants on Rodeo Drive. Another is breakthrough performance: I've never driven a vehicle this big that handles this well.

Sounds impressive, but buyers don't agree so far. Not sure what they could do to get it selling better immediately. I'd gut the interior, add the new V8s and lower the price, but that is just a dream.

M

True. All reviews of the car have been positive, but it seems as though people don't want big SUV's (or minivans in this case) anymore 'cause of soaring gas prices. Also, more and more companies are offering hybrid SUVs. Hybrid is the new trend IMO.

I think the GL will be another R in terms of sales. I see no purpose of that car except for the third row seat.

Well I don't think that is the problem, people turning away from SUVs. I think the look and price of the R is holding it back. I wouldn't be surprised if the GL outsells it quite easily. GM's new full-size SUVs are off the great start so there is still a market left.

M