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From the May/June 2008 Issue

Diesel engines enjoy large market share in Europe. Is this the engine of our deliverance?

For the better part of a century the diesel engine has been looked upon as the gasoline engine’s loud, smelly, and coarse-mannered cousin. While the gas engine grew more sophisticated and quiet, moving in the world of sleek sports cars, sedans, and limousines, the diesel roamed the gritty industrial underworld of dump trucks, bulldozers, and 18-wheelers. 

But now the diesel has been to finishing school. It moves in the best circles, including racetracks. German carmaker Audi stunned the auto racing world in 2006 with a V-12 diesel that won both the 12-hour Sebring endurance race and the grueling 24-hour Le Mans. At the big auto shows on both sides of the Atlantic this year, diesels have been touted for their power, fuel economy, and rapidly evolving “clean and green” credentials. 

At the big Geneva show, Audi again floored the media with a gleaming red R8 Le Mans diesel concept coupe that evoked the maker’s triumphant race cars. Its 500-horsepower turbocharged V-12 diesel propels the car to 60 mph in about 4 seconds. It was an exotic (and successful) effort to rise above the pack in a Europe where crushing fuel taxes have triggered a rush to more-miles-per-gallon diesel cars despite their higher initial cost due to more robust mechanics. 

A UBS/ Ricardo investment study of diesel power notes, “In Europe, fuel prices mean purchasing a diesel engine car has a straightforward economic logic, with the consumer getting sufficient fuel savings to repay the higher upfront purchase cost within a year or two.” Over 53 percent of European new car registrations in 2007 were diesels. That’s about 10 million new cars—from ordinary Audi diesel sedans and quick little Volkswagen Golfs to BMWs, Peugeots, and interesting little Ford and Chevrolet diesels you never see in the United States. Chrysler is marketing a diesel version of its signature 300 sedan in Great Britain. And the Japanese are challenging German diesel dominance with appealing cars like Honda’s immensely popular CR-V diesel crossover. 

In the United States, however, diesels amount to only 3 percent of new vehicle sales and are mostly SUVs and pickup trucks. Many reasons have been offered for why diesel vehicles aren’t more popular—cheap gasoline, initial cost, and increasingly stringent diesel emissions laws. But the most significant reason is likely more psychological than experiential. Americans associate diesels with commercial and industrial transport and dismiss diesel cars as smoky, noisy, hard to start, and slow to accelerate.

This goes back to the oil market shocks of the 1970s and vague recollections of a brief wave of diesel imports that were oversold, misused, or improperly maintained. Uneasy memories remain of some American-made diesels that were cobbled up from existing gasoline engines during the first oil panic. Lodged deep in the American motoring psyche is a great square 1978 Oldsmobile sedan, its blackened rear end spewing fumes as it lumbers forlornly along, making noises somewhere between a bear’s growl and a handful of marbles in a blender. 

Now a new generation of “clean diesels,” able to meet ever-tougher emissions rules while delivering muscular but civilized performance, seem poised to dispel those bad memories and penetrate the American market. The UBS/ Ricardo study predicts sales of new diesel cars and light trucks will rise to 1.5 million by 2012, a 175 percent increase over the next five years. And J. D. Power & Associates sees diesels capturing 14 percent of the U.S. light vehicle market over the next decade. What’s up? 

The remarkable transformation of diesels has come with the market’s rediscovery of their virtues amid concerns over the cost and availability of oil and the environmental impact of automobiles in general. To understand these virtues, it is important to understand the diesel’s history and evolution. 

The transformation of diesels came with the market’s rediscovery of their virtues amid concerns over oil’s cost and availability.

For more than a century the diesel’s elemental appeal has been its hardworking thriftiness. Diesels operate on a simple principle: the more air is compressed, the hotter it becomes. Disperse a fuel—almost any fuel—into this air and it will ignite. Compression plus fuel equals combustion. Spontaneous. Robust. No complex ignition system is needed; no coils, wires, or spark plugs, as in a gasoline engine. 

Diesels burn 20 to 40 percent less fuel than their gas cousins because they operate with significantly higher thermal efficiency, converting more of the total combustion heat into motive power. Diesels cost more because they must be built stronger to contain and channel the extra power they unleash. This extra strength is one reason for their fabled durability. 

Although Rudolf Diesel received an 1893 patent on the “rational heat engine” that would perpetuate his name, he never lived to see his invention propel a car or truck. Beset by financial problems, he disappeared at sea in 1913 in what was very likely a suicide. At the time, the engines licensed under his patent were being employed in factories, ships, and a newly emerging weapon of war, the submarine. It would take years of work by other men, whose names remain obscure, to perfect, tame, and downscale “compression ignition” engines so that they could propel first tractors, then construction equipment and trucks, and, finally, cars. 

One of them was Prosper L’Orange, who began working for Benz (maker of the “Mighty Mercedes”) in 1908 and came up with the idea of the pre-combustion chamber as a way to modulate the diesel’s violent explosive power. 

Meanwhile, engineers at rival Daimler were also working on diesels. By the time Daimler and Benz merged in 1926 they were positioned to dominate the production of diesel trucks. Mercedes-Benz trucks proved to be indomitable workhorses, but their noisy, smoke-belching engines confirmed to the public that diesels were blue-collar machines, unwelcome on the streets where gasoline cars had evolved into discreetly purring vehicles. 

But in a broken and economically struggling Germany after World War I, the proven ruggedness, relative simplicity, and inherent economy of diesel engines appealed to a Daimler-Benz seeking to broaden its share of the automobile market. In the early 1930s, in the teeth of a worldwide depression, the company pressed ahead with its diesel car, hoping it might prove itself first as a taxi. 

Mercedes’s introduction of its reserved-looking 260D sedan in February 1936 was a huge gamble, met with a skepticism that soon turned to surprise. Consider the reaction of British auto reviewer David Scott-Moncrief, who had expected something rough and crude when he traveled to the Mercedes-Benz factory to try out the 4-cylinder, 45-horsepower diesel car. “To my utter hornswogglement the thing proceeded to tick over like a bloodhound lapping soup.”

Indeed, the 260D proved itself reliable and economical. Only a few thousand were produced before World War II, but Mercedes would go on to become a world leader in the steady improvement of diesel cars and trucks. By the time Daimler-Benz celebrated its 100th anniversary in 1986 it had sold well over 3 million diesel cars. 

A new generation of ‘clean diesels,’ able to meet tougher emissions rules and deliver muscular but civilized performance, is poised to penetrate the U.S. market.

Survey the world of automotive manufacturers and you see that the Europeans, particularly the Germans, have concentrated on diesel development while improving the efficiency of gas engines. The Japanese have also been coaxing the gas engine to new heights while combining it with electric drive in hybrids, like the Toyota Prius. As for the Americans, they appear to be hedging their bets, trying to cover all the bases—improving gas engines but dabbling in diesels and hybrids. Ford, for instance, plans to offer a diesel engine in its F-150 pickup, the best-selling vehicle in the United States, by 2010. 

Although Cadillac will offer a V-6 diesel in a European version of its CTS sedan next year, there are few American diesel sedans on the immediate horizon; the specter of the fuming Olds still haunts Detroit. And even as an array of foreign makers are poised to enter the U.S. market in the coming model year, some industry analysts see diesels as a hard sell. In a recent study by J. D. Power & Associates, Americans considering a diesel said they would expect an improvement in gas mileage of 15 miles per gallon over a comparable gas car, which could be a tall order. They expressed a willingness to pay as much as $1500 extra for a diesel, but studies show that the real cost premium over a gas car will be at least twice that. 

Whatever happens, the modernization of diesels has been a technological tour de force with happy implications all over the marketplace. The ever more advanced electronics, materials, and engineering genius that have refined combustion, isolated or reduced engine noise, and virtually eliminated most emissions in diesels are part of a vital and expanding synergy affecting all power train research. 

And now diesels are being melded into hybrid technology. Volkswagen recently unveiled its Golf TDI Hybrid, combining a 27-horsepower electric motor with a 74-horsepower turbodiesel. It claims the hatchback four-door can average about 70 miles per gallon. And technological cross-fertilization is at work in something called HCCI, or homogenous charge compression ignition. This is a best-of-both-worlds engine, now being researched and tested by GM, Ford, Honda, Mitsubishi, and others, that employs the thermal efficiency of a diesel’s compression ignition but burns gasoline. 

For the near future and for a lot longer than many people realize, the good old gasoline engine, its efficiency rate improving about 1.5 percent a year, will dominate personal transportation. But improved diesels offer consumers greater choice, demonstrating once again that the market’s institutional ingenuity and innate optimism turn problems into opportunities. 

Ralph Kinney Bennett covered national and international affairs for Reader’s Digest in its Washington bureau for 34 years.

Image courtesy of Audi of America.

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