Volkswagen TouaregClick to enlarge picture

Three engine choices, one a V10 diesel, are on tap for VW's sport-utility vehicle, the Touareg.

Automakers are readying new diesel-powered vehicles for U.S. consumers, with some models starting to arrive in showrooms during 2004.

Mercedes-Benz, which in 1936 debuted the 260D, the world's first diesel car, is offering its first diesel model in the U.S., the 2005 E320 CDI sedan.

With a highway fuel economy rating of 37 miles a gallon and a whopping 369 lb-ft of torque coming on as low as 1800 rpm, the six-cylinder-powered E320 CDI can appeal to both fuel-conscious buyers and sport-minded drivers.

Indeed, the E320 CDI's torque is 59 percent greater than the 232 lb-ft at 3000 to 4800 rpm of the E320 gasoline engine. The diesel sedan's estimated 0-to-60-mph time of 6.8 seconds is better than the 7.1 seconds of the Mercedes E320 gasoline model.

Not to be outdone, Volkswagen of America Inc. is offering a diesel V10 engine in its Touareg sport utility that provides an amazing 553 lb-ft of torque at 2000 rpm and has added a diesel-powered Passat sedan to the lineup.

In the 2005 model year, Jeep adds a 2.8-liter turbocharged four-cylinder diesel to its Liberty SUV. The 295 lb-ft of torque from this power plant is more than the 165 lb-ft from the Liberty's gasoline-powered four cylinder and more than the 235 lb-ft of torque from the Liberty's 3.7-liter gas V6.

While larger SUVs such as the Ford Excursion have been offered with diesel engines over the years, the Liberty marks the first smaller-size SUV in the U.S. to include a diesel option.

All this comes as U.S. consumers are becoming more familiar with fuel-efficient gasoline-electric hybrids and begs the questions: Why diesels—and why now?

Diesels Didn't Disappear

Many American consumers might have the impression that diesel-powered vehicles, for the most part, have disappeared. It's true that interest in diesels in this country, particularly in cars, has faded since the early 1980s when car buyers were more focused on fuel efficiency. Back then, even General Motors Corp. built and sold diesel-powered cars in this country.

As the memory of the oil shocks of the 1970s went away, Americans began to eschew diesels in favor of internal combustion engines that burn gasoline. Truth was, the old diesels could be loud, making the usual diesel engine racket under the hood. They could be smelly, with telltale fuel odors emitting from the tailpipe.

"The technology of the time left a bad taste in the mouths of many and a lot of bad memories of smokey, smelly, clatter-trap cars," acknowledged Dieter Zetsche, president and chief executive officer at Chrysler.

Many consumers didn't like going to truck stops to get their diesel fuel. Trouble was, many neighborhood filling stations didn't have diesel pumps.

With publicized concerns cropping up over the years about diesel emissions possibly being deleterious to health, it's not surprising that the demand for diesels in this country fell. However, diesel demand continued in the large pickup truck segment, where torque, towing performance and long-term durability are areas where diesels can excel.

Europe Embraces Diesels

Diesels also didn't disappear in Western Europe, where they are in an estimated 35 percent to 40 percent of new models sold.

Indeed, anyone who has visited France or Austria lately can attest to the widespread use of diesel cars. In France diesels are in an estimated 60 percent of new cars sold; in Austria, it's 70 percent or more.

Chief reasons for popularity of diesels in Europe: The price of diesel is lower than that of gasoline, and diesel engines have greater fuel efficiency than gasoline engines. (It helps that filling stations often provide free gloves to keep drivers' hands from getting that diesel smell on them.)

Europeans also have come to prize the new diesel engines for their strong torque —an amazing amount of get up and go can be found in a diesel car—and for their durability.

Diesel Progress

Diesels has been improving and aren't the same as they were about 20 years ago.

Today's diesel engines for cars tend to use Common-rail Direct Injection technology—which is what the "CDI" in the Mercedes E320 CDI model stands for, for example. This rail is a shared delivery "pipe" for all fuel injectors and allows the diesel fuel to get into engine cylinders at a consistent, very highly pressurized rate - roughly 23,000 psi in the E320 CDI.

Electronic fuel injection systems used in today's diesel cars allow for varied injection timing and adjustment of the quantity of fuel injected, so vehicles can better respond to driver demands. Diesel engines for today's cars also tend to be turbocharged to ensure strong performance characteristics.

The electronics and common rail technology, along with newer particulate filter installations, have helped the newer diesel engines better meet ever-stricter diesel emission regulations. Pollution rules in five states—California, New York, Maine, Massachusetts and Vermont—still preclude the 2005 E320 CDI as well as some of VW's diesel-powered vehicles from being sold there.

Mercedes officials said they plan to offer the diesel E-Class in those states in 2006 for the 2007 model year, after U.S. regulations require refiners to create cleaner diesel fuel, with less sulfur content than what is currently allowed.

U.S. Changing

No one in the auto industry is predicting Americans will join Europeans in their level of interest in diesels. Nonetheless, there are signs that things here are changing.

As gasoline prices have risen in the last few years, Mercedes officials noted they get regular requests from U.S. consumers who remember Mercedes diesel-powered cars.

There are plenty to remember, since in the early 1980s more than 75 percent of the Mercedes cars sold in the United States were diesel-powered. The last Mercedes with a diesel engine in this country was the E300 Turbodiesel, which left the market in 1999.

Bharat Balasubramanian, vice president of engineering technologies and regulatory affairs at the Mercedes car group, said more than 50 percent of the diesel cars sold in the U.S. are "still running here on the roads."

Volkswagen, which continued to sell diesel-powered versions of its Golf and Jetta models over the years and currently offers a diesel in its New Beetle, says its diesels are well received and never languish on dealer lots.

Indeed, a base 2004 VW Golf GL four door with 2.0-liter four-cylinder gasoline engine and manual transmission is rated at 24 miles a gallon in city driving and 31 mpg on the highway. A 2004 Golf GL four door with 1.9-liter turbocharged four-cylinder diesel engine is rated at 38 mpg in the city and 46 mpg on the highway.

Note the 100-horsepower diesel engine in the Golf generates 177 lb-ft of torque starting as low as 1800 rpm and continuing to 2400 rpm for good zip and response, while the 115-horsepower gas engine in the Golf GL develops only 122 lb-ft of torque at 2600 rpm.

The U.S. Environmental Protection Agency ranks VW's diesel-powered New Beetle as the most fuel-efficient subcompact car for 2004, while the diesel-powered Jetta wagon is the most fuel-efficient small station wagon.

These days, VW is offering a diesel engine for the Passat sedan, as well as boosting the torque of the Touareg with a diesel V10.

Challenges Ahead

Consumers need to know and be convinced that diesel engines of today aren't the same as the noisy ones from 20 years ago.

The best way to evaluate diesels is to test drive the new models that have them and compare these vehicles, back to back, with gasoline-powered versions of the same models.

The results could surprise you. For example, the '05 Mercedes E320 CDI contains extra soundproofing and engine technology to help reduce the usual diesel engine rattle, or clatter, that's usually heard under the hood.

As a result, some consumers might be hard-pressed to notice, by the sound, that this new model is a diesel. Tests by Mercedes show the car is the quietest diesel the company has ever offered in the U.S., with sounds at idle a mere 44 decibels compared with 42 decibels for the comparable gasoline-powered E-Class sedan. At full throttle, the diesel model actually is slightly quieter than the gasoline model, with noise measured at 72 decibels vs. 76 decibels from the gasoline engine.

Meantime, automakers are examining price in the whole consumer-appeal equation.

VW's Touareg with 310-horsepower V10 had a starting MSRP at introduction of more than $57,000. This is some $15,000 more than a Touareg with a V8 that has 310 horsepower but only 302 lb-ft of torque between 3000 and 4000 rpm.

Diesel cars in Europe typically come with a smaller price premium of $1,000 or more vs. a comparable gasoline model.

In the United States, VW's 2004 diesel-powered Golf GL hatchback with a manual transmission has a starting MSRP of more than $17,000, which is some $1,600 higher than a comparable gasoline-powered Golf GL.

Mercedes put a $1,000 price premium on its 2005 E320 CDI over the 2004 E320 gasoline-powered six-cylinder sedan. At introduction, the E320 CDI had a starting MSRP of just over $49,000.

Despite all the changes, though, only time will tell how receptive U.S. consumers are to the rising number of diesel offerings.

Ann Job is a writer for T&A Ink.

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