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THE BASICS

Base price/as tested: $58,000 to $70,000 (est.)

Fuel economy: Not announced, but probably about 16 m.p.g.

THE SPECIFICS

Drivetrain: All-wheel drive

Seating: Seven occupants

Horsepower: 335

Torque: 339 lb.-ft.

Overall length: 200.3 inches

Wheelbase: 121.1 inches

Height: 72.4 inches

Width: 75.6 inches

Curb weight: 5,249 pounds

NAPA VALLEY, Calif. — Does the world really need another big, luxurious SUV with off-road capabilities that very few of its drivers will ever use?

No.

Does Mercedes-Benz need exactly this vehicle in its lineup?

Absolutely.

According to the company’s study of people who own its cars, more than one-third also own a large SUV built by another manufacturer.

And more than a quarter of those who used to drive Mercedes’ mid-size M-Class SUV have opted for another automaker’s big rig.

Porsche was in a similar car/SUV dilemma in 2002, when it decided to expand into the SUV market. The move greatly boosted overall sales.

And so, here comes the 2007 Mercedes-Benz GL-Class, featuring an extremely large SUV for seven passengers, with 7,500 pounds of towing capacity. That’s enough to tow a 30-foot boat or a three-horse trailer, said Ron Mueller, head of product management for the GL-Class.

We drove it out of San Francisco and into wine country. It was exceptionally smooth and quiet on the highway, very stable on twisting canyon roads, and capable in limited off-road testing that featured a couple of steep hills and some slick mud.

It was particularly interesting to discover that this behemoth, which weighs more than 2 1/2 tons, never felt big during open travel. I doubt its 200.3-inch overall length would lend itself to serious off-roading in tight quarters, but the engineering beneath would certainly take it as far as size would allow.

The GL-Class is ably powered by a 4.6-liter V-8 with 335 horsepower and 339 lb.-ft. of trailer-tugging torque.

It is linked to what is becoming one of my favorite transmissions, the Mercedes seven-speed automatic. It is a full-time all-wheel-drive vehicle (a two-wheel-drive could come later).

This standard drive train alone should be sufficient for those who want to haul family and gear to the ski house, the hunting lodge, or the backwoods trout stream. For those who seek more deep-crawling capability, an off-road package is an option, bringing with it a two-speed transfer case, locking center and rear differentials, and an advanced air suspension system that can raise the vehicle for a foot of ground clearance or two feet of creek-crossing protection.

To its credit, Mercedes joins a small but growing list of manufacturers who make a key bundle of safety features standard. On this model they include traction control, adaptive front air bags, seat-mounted side air bags for the first two rows, and window-curtain air bags for all three rows.

The outside is not particularly distinct (I thought it looked similar to a Toyota Sequoia). The inside, with leather, bird’s-eye maple wood treatments, power/heated front seats, a 60/40-split center row and 50/50-split third is both elegant and functional.

Major options, besides the off-road package, include:

Bi-Xenon headlights that move to see around curves.

Fog lamps that also illuminate corners.

A Harman Kardon upgraded sound system with 11 speakers.

A rear entertainment package with multiple-screen DVD.

Three-zone air conditioning.

A power tailgate (a great feature, since it is so huge).

Heated second-row seats.

A navigation system.

Definitive pricing has not been announced, but expect to pay in the high 50s to the low 70s when the GLs start rolling into dealerships in May.

It will compete with SUVs like the Porsche Cayenne, Land Rover Range Rover, Cadillac Escalade, Lincoln Navigator, and Lexus LX 470.

Considering that list, you can understand Mueller’s simple response to a question about why Mercedes was getting into the big/luxury/SUV market now:

”It’s about time.”

This probably won’t be the end of adaptation for Mercedes-Benz in the big SUV market.

Already there is talk of a diesel version as the company goes heavily into the US market with diesels virtually across the board — something it did it successfully with all-wheel drive — and a possible hybrid gasoline-electric model.

If Porsche can grow by building SUVs, Mercedes can certainly hold onto more of its customers, and maybe even sell to those outside the brand, by offering them an opportunity to make the high climb into a big ride.

Royal Ford can be reached at ford@globe.com.

© Copyright 2006 Globe Newspaper Company.