The 2009 Mercedes-Benz GL320's diesel powerplant wrings impressive mileage out of every gallon of fuel. The federal rating for this nearly 17-foot-long SUV is 17 mpg in city driving and 23 mpg on the highway.
In my real-world test drive, I managed 23 mpg in combined city/highway travel. I went nearly 600 miles and still didn't need to fill up the 26.4-gallon fuel tank.
Best of all, owners don't give up a thing in luxury accouterments and four-wheel-drive capability.
The 3-liter, direct-injection, turbocharged inline six-cylinder in Mercedes-Benz's largest SUV is certified to be clean enough -- with today's improved low-sulfur diesel fuel -- to qualify to be sold in all 50 states.
The fuel savings, advanced pollution control and roomy, luxury interior come at a price, though.
The GL320, which is a tad smaller overall than a Cadillac Escalade SUV, has a starting price, including destination charge, of $59,075.
That is $4,000 less than a base, gasoline-powered Escalade and is less than the base, gasoline version of the GL-Class, both of which have V-8s.
The Mercedes-Benz also has a lower price than the 2009 Lexus LX 570 with gasoline V-8, which goes for $76,730. The smaller 2009 BMW X5 with diesel six-cylinder and even better fuel mileage rating -- 18/26 mpg -- starts for less, just over $52,000.
Mercedes-Benz also added its BlueTEC diesel powerplant to the E-Class sedan and M-Class crossover SUV to boost mileage and attract buyers who can afford to waste fuel but don't want to.
Diesel engines have long been known for their thrifty use of fuel and their durability. They're also known for quick, strong torque, and it's definitely one of the pleasures of the GL320.
Horsepower is just 210 in this big, more than 5,000-pound people hauler, but torque peaks at 398 foot-pounds at a low 1,600 rpm. This is more than the 339 foot-pounds starting at 2,700 rpm generated by the 335-horsepower, 4.5-liter, gasoline V-8 in the Mercedes-Benz GL450, which is rated at just 13 mpg in city driving.
The power in the diesel-powered test car comes on in smooth, responsive fashion, and it's so easily managed that this SUV moves quickly to snag openings in traffic in congested highway situations.
It takes awhile to get the hang of the short stalk near the dashboard that's the newfangled shifter. To put it into "Park," for example, there's no moving the lever up. Instead, a driver pushes the "P" button.
All my passengers noticed how quiet it was inside. Many didn't notice any diesel sounds. I heard a bit of the typical diesel engine racket only when I had windows down or when I was standing outside.
The interior -- with $6,600 optional leather package -- was impeccable. There was a quality and pampered feel all around.
The maximum cargo space is a healthy 83.3 cubic feet.
The navigation system seemed clumsy to use, with a lot of effort required to put in destination addresses. It wouldn't work unless the radio was turned on. The same was true for the rear-view camera.
The vehicle rides high above the road. This is good for front and side views out of the vehicle, but there's noticeable body lean during turns and in curves.
The suspension is nicely tuned to allow some feedback from the road to the driver, but it's not enough to bother passengers or make them feel bumps. At slow speeds in off-road terrain, however, the vehicle can jiggle passengers considerably.
I was pleasantly surprised to see how small the turning circle is for this large SUV with 20-inch tires.
The four-wheel drive is permanent and doesn't require any buttons to be pushed by the driver, and it capably powers through even most off-road situations.
Although the government hasn't done crash tests on the GL-Class -- diesel or otherwise -- the vehicle comes well-equipped with safety items including nine air bags, rollover sensors, electronic stability control and four-wheel traction control. Consumer Reports says the GL-Class has a poor reliability rating.
THE VEHICLE: 2009 Mercedes-Benz GL320 BlueTEC, a front-engine, four-wheel-drive, seven-passenger, full-size sport utility vehicle
BASE PRICE: $58,200
DESTINATION CHARGE: $875
AS TESTED: $71,125
ENGINE: 3-liter, double overhead cam, turbocharged, direct-injection diesel, inline six-cylinder producing 210 horsepower
TRANSMISSION: Seven-speed automatic
EPA MILEAGE: 17 mpg city, 23 mpg highway
LENGTH: 200.6 inches
WHEELBASE: 121.1 inches
CURB WEIGHT: 5,313 pounds
BUILT IN: Tuscaloosa, Ala.
OPTIONS: Premium package I (includes Keyless Go, navigation system, power driver's seat and front passenger's seat with memory, Sirius satellite radio, Harman/kardon surround sound system), $6,600; leather seat trim with burl walnut interior trim, $2,130; rear-seat entertainment system, $1,850; adaptive damping system, $750; Capri Blue metallic paint, $720