(FORTUNE Small Business) – It is either the largest station wagon you ever saw or the smallest minivan. No matter what you call it, the Mercedes-Benz R500 answers a question most drivers haven't considered until now: How does a Mercedes comfortably transport six adults? Another unasked question: Would you spend up to $70,000 to do that?

Mercedes thinks the R500 is so revolutionary that it deserves its own letter-class designation. From a customer's point of view, you can think of it as a stretched station wagon. At 203 inches, it is a foot longer than Mercedes' biggest wagon, the E500, and the roof has been raised seven inches to accommodate adults in the third row of seats. (They would want to sit back there only for short trips, though.) The styling is most diplomatically described as distinctive. Whereas the E-wagon is as invisible as a Stealth fighter, the R-Class makes a definite statement. From the side, a powerful swoosh sweeps through the beltline, serving as counterpoint to the sharp arc of the rear window that disguises the high roof. Less appealing are the views from the front and the rear, where the heft of the R500 becomes most apparent.

Slip into the driver's seat, and you are surrounded by fine leather, glorious woods, and immaculately detailed controls. Observant drivers will notice two big changes compared with the E-wagon: The gearshift has been relocated to the steering column, and two giant cupholders have been excavated from the now empty space in the center console. The 5.0-liter V-8 produces 302 horsepower and gets to 60 mph in 6.5 seconds, and the electronically controlled seven-speed transmission provides seamless shifts. Some of my pals thought the R didn't feel like a "real Mercedes," but it sure did to me: smooth, powerful, and understated. My highway mileage ran close to 19 miles to the gallon.

It is too soon to tell if Mercedes has eliminated the bothersome electronic gremlins that have bedeviled recent models. One owner complained about the electric seats in his E-wagon, which "go nuts on their own." But if you have $69,310 (the sticker on my tester, which came loaded with options), this one will satisfy your aesthetic and functional needs. Prices for the standard, all-wheel-drive R500 start at $56,275, $6,500 less than a four-wheel-drive, V-8 powered E-wagon. Use the extra money for a long weekend away with two other couples. For the sake of the pair in the back row, however, you might not want to go too far.