- The Washington Times - Wednesday, October 19, 2005

Minivans have peaked. Big SUVs are tapering off. Sedan sales are dipping. So what kind of vehicle will become the next hot seller in the automotive marketplace?

Mercedes-Benz is betting that its innovative R-Class sports tourer is a candidate. But describing what segment the R-Class fits into is daunting.

It is not a minivan, SUV, station wagon or sedan. However, its size, performance, all-wheel-drive utility and people-carrying capacity wed the key features of all those types. Competitors for the R-Class could include the Chrysler Pacifica, except it is not a luxury vehicle. The Cadillac SRX might also be roughly comparable to the R-Class, but is 10 inches shorter.

Mercedes, however, thinks its new sports tourer is the first of a totally new class of vehicles. Audi and Lincoln, among others, are reported to have competitors for the R-Class in the works.

The R-Class looks like a sports wagon on steroids. It is muscular and brawny like an SUV, yet its aerodynamic design rivals that of a sports sedan. The 0.31 coefficient of drag confirming its sleekness also translates into low wind noise even at high cruising speed.

Even longer than the S-Class (by 1 inch), the R-Class is the longest Mercedes offered. A generous 64 percent of that length is available for occupants.

The interior has three rows of comfortable seats that can carry six occupants. Both rows of rear seats can be folded down to provide the cargo-carrying capacity of bigger SUVs and minivans. In addition, the second-row seats can be adjusted fore and aft to provide up to 39 inches of legroom. There are about 30 inches of space between the second and third rows.

Mercedes vehicles are not only known for comfort, but for state-of-the-art engineering and powerful engines. The R-Class doesn’t disappoint in these areas. A seven-speed automatic transmission partners with either a powerful V-6 or V-8 engine. Mercedes engineers also plan to offer an advanced CDI diesel engine in this vehicle.

The seven-speed transmission has a wide spread of gear ratios between first and seventh that gives the R-Class swifter acceleration and smoother downshifts.

It allows smaller increases in engine speed as the vehicle accelerates. This maximizes fuel economy and provides very fast reaction time to accelerator pressure.

The computer that controls the transmission allows it to skip as many as three gear ratios when it downshifts. It can downshift from seventh to fifth, or from sixth to second, for instance. The shifting action is very smooth and the driver doesn’t feel any jerkiness in the transition from one gear stage to the next.

The transmission’s hydrodynamic torque converter contains a lockup clutch that also increases fuel efficiency and eliminates converter slippage. When the lockup clutch is engaged, it simulates the direct connection and fuel efficiency of a manual transmission. Also noteworthy is that the lockup clutch engages in all seven gears, compared to many transmissions that only lock up in top gear.

If you’re searching for a conventional shift lever in the R-Class, forget about it. The electronic shifter is a small handle just to the right of the steering wheel. You lift the stalk to shift into reverse and push it down to engage drive. There’s also a button that you have to push to engage the parking gear.

The back of the steering wheel has manual shift buttons that you touch gently to shift gears. There’s no need to use the shift lever at all to control the transmission manually. There just aren’t any forward gear positions.

Just in case you select the wrong gear manually, the brainy transmission controller prevents downshifts that would cause the engine to overrev.

The 3.5-liter V-6 generates 268 horsepower. If that’s not enough power for you, there’s a 5.0-liter V-8 that cranks out 302 horsepower. The V-6 is the first Mercedes engine of its size to use double-overhead camshafts. It produces 258 foot-pounds of torque from 2,400 to 5,000 rpm. At 1,500 rpm, the V-6 develops 87 percent of its torque.

The V-8 has what Mercedes engineers call tumble flaps in the intake passages near the combustion chamber. The flaps pivot open under partial load and improve combustion by creating turbulence around the intake valve and in the combustion chamber.

Under full engine load, the tumble flaps recede into the walls of the intake manifold to provide better combustion and improved torque.

Mercedes engineers say the main result of the tumble flaps is to increase fuel economy by as much as 2 percent.

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