- The Washington Times - Friday, July 18, 2008

For 2009, Mercedes-Benz is offering three vehicles with its new BlueTEC diesel engines — the full-size GL320 and mid-size ML320 sport utility vehicles, and the R320 crossover utility vehicle. They emit so few pollutants that they can be sold nationwide, even in California and its fellow-traveler states with clean air requirements stricter than those of the federal government.

“We’re a baby’s breath away from a zero-emissions vehicle in California,” said William Craven, the general manager of regulatory affairs for Mercedes-Benz. That’s a long way from diesel engines of yore. They were balky, noisy, nasty smelling and polluted the air not only with noxious fumes but sooty particulates as well.

But Mercedes has been a pioneer since the 1930s in diesel engine passenger car technology — a territory it has never abandoned. Back in the early 1980s, about eight in 10 Mercedes vehicles were sold with diesels.

Instead of spark plugs, as in gas engines, diesels use the heat from high compression to ignite the fuel-air mixture. They are stronger, generally last longer and deliver better fuel economy than their gasoline counterparts, which is why they are used in long-distance trucks. Diesels also are popular in Europe, where fuel prices are close to double those in the United States.

Moreover, the Mercedes technology has advanced to where anybody would be hard-pressed, from the driver’s seat, to detect much difference between a gasoline engine and a BlueTEC diesel. The only way to tell is to stand near the front of the car, where you can hear a slight diesel clatter.

In fact, the diesels deliver such enormous torque, or low-rpm twisting force, that they feel more powerful off the line than their gas-engine counterparts. For example, the V6 diesel in the ML320 has 210 horsepower and 398 pounds-feet of torque. Its ML350 gasoline counterpart has 268 horsepower but 258 pounds-feet of torque.

Punch the pedal at a stop sign with the ML320 BlueTEC and, despite its weight of nearly two and one-half tons, it fairly leaps forward. Once moving, there’s no lack of power.

The same engine is used in the heavier R320 and GL320 but they feel nearly as spirited.

Despite the fact that diesel fuel is unaccountably higher priced than gasoline, you can still make a case for ordering one of the BlueTEC diesels, though it’s becoming less persuasive as the odds change with rising fuel costs.

Mercedes charges a premium of about $1,500 for the diesel engine in all three of the new utility vehicles.

Figuring annual mileage of about 15,000, the ML320 diesel, rated at 18 miles per gallon on the EPA’s city cycle, and diesel at about $4.75 a gallon, the fuel cost for one year of driving would be approximately $3,958.

The ML350, with its rating of 15 miles to the gallon and premium gasoline at about $4.30 a gallon, would cost about $4,300 for the year.

With the diesel, the savings would amount to about $342. It means that it would take more than four years, assuming prices don’t change, to recoup the additional cost of the diesel model.

If you do the calculation using the EPA’s highway consumption figures of 24 miles to the gallon for the diesel and 20 for the gas engine, the annual saving comes to about $255.

There’s one additional cost with the new BlueTEC diesels. To achieve the low emissions, they inject urea, a nitrogen-rich organic compound, into the combustion process. The urea is carried onboard in a tank that holds about seven gallons, and it is designed to be replenished at the same time as a periodic oil change.

If an owner does not refill the urea tank, he will receive warnings of an impending shutdown. If that is ignored, the vehicle eventually will not start.

Despite all that, Mercedes officials believe that diesels will account for about 15 percent of the sales of the GL, ML and R class vehicles. They argue that fuel price is only one of many elements that influence a buyer’s choice.

Moreover, Mercedes does not market to the hoi polloi. Virtually all of its vehicles reside in the luxury class, so their sales are not huge.

Prices start north of $45,000 and soar upward from there, especially when options are added, as they almost always are. Of the three BlueTEC diesels, the ML320 exhibits the most changes.

First introduced as a 1998 model, the ML has morphed from a body-on-frame, truck-like SUV to a softer and plusher unit-body vehicle that is more competitive with machines like the Lexus RX.

The new ML320, including the BlueTEC, has a redesigned front end, new interior appointments and a full range of state-of-the-art safety equipment.

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