No need for hybrids

The idea of a diesel-powered Mercedes might surprise some, but actually, they've been around for quite a while. The German automaker's line-up has been sprinkled with oil-burning models in Europe, but in North America, only one or two at a time crossed the ocean.

The idea of a diesel-powered Mercedes might surprise some.

But do diesel-powered cars still evoke the impression that they're smelly, noisy, dirty and underpowered? Maybe, but recent offerings from a couple of audacious manufacturers have proven that diesel engines that are being developed now are quite modern. In the late '70s, automakers scrambled to produce diesels because of the oil crisis, and the result was pretty disastrous.

Buckets o' torque

Buying a 215-hp, 3.0-liter V6 under the hood of a 5,313-lb (2,410-kg) truck might seem masochistic, but the torque rating of 398 lb-ft, which peaks from 1,600 to 2,400 rpm, makes up nicely. Since low-end torque is great for quick acceleration, the GL320 strolls from 0 to 100 km/h in 9.8 seconds. Not as blazingly fast as the GL550 which blasts to the same speed in 6.5 seconds, but still fairly quick.

In normal driving, however, the diesel engine's power delivery is smooth and linear. No one who rides aboard guesses that it's not a conventional gasoline engine up front. At idle, the smell of the exhaust still reveals the diesel fuel combustion, and when firing up the engine in cold weather, it's a little noisy.

At a steady highway speed, you'll likely consume about 10.0 L/100 km, and in the city, roughly 15.0; my average is 12.7 L/100 km. That's not bad at all, because the GL450 and GL550 will easily consume an average of 15 liters for every 100 km. However, I'm pretty sure fuel economy is not a major concern for someone who's purchasing an $80,000-plus SUV.

The GL320 strolls from 0 to 100 km/h in 9.8 seconds.

Smooth drive

The AIRMATIC DC suspension that equips every GL-Class works well, absorbing road imperfections and transmitting only slight motions through the cockpit. It also levels the truck when you load it up. The GL320 doesn't offer the sporty driving dynamics as, say, a BMW X5 or a Porsche Cayenne, but then again, it's a smoother road tripper. Barrelling down highway off-ramps, AIRMATIC DC pumps up the outside shocks to keep body roll in control.

The seats and the dashboard are covered in synthetic leather.

You can also raise or lower the suspension height at the touch of a button on the dash. The ride height also drops above 120 km/h to improve aerodynamics. The adaptive suspension system with 3 selectable driving modes (Auto, Comfort, Sport) isn't available on the GL320 CDI, but then again, this type of gadget isn't a must-have feature.

The 4MATIC all-wheel system splits power 50:50 in normal conditions, but can distribute torque to any wheel it wants when slippage is noticed.
Well-appointed cabin

The luxurious cockpit of the GL320 CDI is quite a place to spend time in. The seats and the dashboard are covered in synthetic leather, what Mercedes calls Artico. Genuine leather for the seats is a $2,500 option, which seems like a rip-off in a vehicle of this price; environmentalists will approve that a cow won't be slain to cover your seats, though. Real wood and silver trim brighten up the otherwise dark environment.

The controls are generally well-positioned, but even after a week, I still can't get used to the location of the gear selector. Also, the radio buttons were unnecessarily fussy, and the tiny joystick used to change stations and such often slips out of your grasp.

The square shape and generous proportions of the GL-Class means lots of space for occupants. In the second row, passengers will benefit from lots of leg and shoulder room; the third row seat can be used by adults if they are willing to rub their knees on the 2nd-row seatback.

Also, access to the rearmost seat isn't simple, as only the right-side portion of the 2nd-row bench can be flipped forward. Fold down all rear seats, though, and you get a big cargo hold, but not as big as in the GL's rivals.

The controls are generally well-positioned.

Competition

My no-options GL320 CDI costs $71,500, while the GL450 sells for $82,500 and the full-tilt GL550 goes for $91,000. Mercedes-Benz clearly stated the GL's direct rivals: the Cadillac Escalade and Lincoln Navigator. There are a couple more full-size luxo-SUVs on the market, too. Anyway, here's the pricing breakdown:

Cadillac Escalade, $76,960
Hummer H2 SUV, $72,295
Range Rover, $100,900
Lexus LX 570, $84,600
Lincoln Navigator, $73,299

None of them offer a diesel engine, but the Escalade will soon be available with a hybrid powertrain.

Real wood and silver trim brighten up the otherwise dark environment.

Conclusion

The GL320 CDI has all the virtues of its more-expensive brethren, but with an engine that delivers better fuel economy, although the difference isn't really enormous. I have the feeling that if there was a gas-powered base model alternative, not many people would choose the diesel. Why?


Diesel-powered vehicles are no longer smelly and dirty, but diesel fuel pumps at gas stations still are. Every time I fill up at a diesel pump, there usually are puddles from people trying to top off their tank and overflowing it. The pump itself is covered with a quarter-inch of oily grime, and I leave the station smelling like an old furnace. For me, a diesel car or truck is a turn-off just for that. I could always stop at a full-service station, though.

Diesel or not, the GL-Class is a competent big SUV that glides its numerous occupants down the road in luxury and smoothness. If you like driving a vehicle that feels built from a solid billet of steel, you'll probably like the GL320 CDI.

The GL320 CDI has all the virtues of its more-expensive brethren, but with an engine that delivers better fuel economy.