Defining Diesel

"You drive a what?"

"A diesel."

"A diesel?"

That's the response I usually get, along with a look of incredulity, when I tell friends that I drive a VW Golf TDI (turbodiesel direct injection).

It's not that they're accustomed to seeing diesels only at truck stops. It's that they expect me, an eco-conscious citizen bent on living a more sustainable lifestyle, to be driving something different. I then spend the next five minutes explaining that instead of driving a slow, loud, smoke-belching beast like they remember from the '70s, I drive a sleek, quiet speedster that runs on biodiesel and used vegetable oil and is as easy on my wallet as it is on the environment.

Yes, the diesel engine has come a long way from its bulky beginnings in the early 1900s. While its automotive future faltered toward the end of the 20th century here in the U.S., it is presently experiencing a resurgence of sorts. Still the darling of the trucking industry the world over, the diesel engine's strength, reliability, efficiency and ability to run on alternative fuel, coupled with the EPA's new National Clean Diesel Campaign, has car buyers reconsidering diesels as their future mode of transportation.

So what's changed, you ask? Let's take a look.

Peanuts

Dr. Rudolph Diesel (1858-1913) unveiled his compression engine at the 1898 Exhibition Fair in Paris. There, amid the grandeur of the world's fair, the talk was not only of the engine's impressive 75-percent efficiency rating (compared to the steam engine's 12 percent and the gasoline engine's 25 percent), but of the fact that it ran on plain old peanut oil.

Unlike the gasoline engine, which runs on combustion (gas is pumped into the pistons and ignited by a spark), Diesel's engine ran on compression (air is compressed to the point where it becomes extremely hot, thereby igniting the fuel mixture when it is injected). The result was an engine that was stronger, simpler and more efficient.

Seems that besides being a genius, Diesel was a bit of a socialist as well. It was his hope that by fueling an engine with biomass (plant material, vegetation or agricultural waste), he could take the power away from big industry and put it back into the hands of the everyday farmer and small businessman. "The use of vegetable oils may seem insignificant today, but such oils may become in the course of time as important as petroleum and the coal tar products of the present time," he said in 1912.

Diesel decided to travel abroad and share his engine design (including its uses in submarines and naval ships) with the Queen's navy. Unfortunately, while crossing the English Channel, he disappeared over the side of the ferry and was never heard from again. Conspiracy theories abound as to who or what caused his disappearance.

After Dr. Diesel's demise, his engine continued to be used throughout Europe and slowly made its way to the U.S. Due to the large injection pumps of the time, however, they were extremely cumbersome and were primarily used in heavy industry and shipping.

In 1919, Clessie L. Cummins, a mechanic here in the States, purchased the rights to the diesel engine and began work on making it smaller and more stable for use in automobiles. Around the same time, the oil conglomerates, which were just beginning to take shape, introduced a byproduct of gasoline distillation that would successfully run a diesel engine and marketed it as "diesel fuel." The new fuel became the standard for compression engines, and biomass fuel faded to the back of the pack.

Cummins continued to work on improving the diesel engine to the point where it began to make an impact in the automotive market. In the late '20s and '30s he set land speed records, drove cross-country in a diesel-powered vehicle for $11.22, and established an endurance record of 13,535 miles at the Indianapolis Speedway, after which, it is presumed, he took a long and well-deserved nap. The diesel was beginning to come into its own, and today the Cummins engine is one of the more popular diesel engines in use around the world.

Jumping ahead to the 1970s, the oil embargoes gave diesel engines their next big boost here in the U.S. Starved for oil, car buyers began to look for more efficient alternatives, and diesel was there for them. GM became the first American car company to make a diesel passenger vehicle, earning it more than 60 percent of the market. Unfortunately, most of the cars it sold had gas engines that had been converted to diesel, causing them to be loud, dirty and problematic. Having developed a bad name, diesel passenger cars quickly faded from the American landscape, and gasoline engines returned as the norm.

Diesel gets clean(er)

While the '70s hurt the diesel engine's reputation here in the U.S., they never faded from the European scene. Last year, more than half of the luxury vehicles sold in Europe were diesel-powered. Now, with fuel prices on the rise and efficiency gaining momentum in consumer car-buying decisions, the diesel is primed for a return to the U.S. But the vehicles we are about to see won't be like any of those that came before.

Thanks to the EPA's new National Clean Diesel Campaign, diesels have undergone significant changes. The new engines, dubbed "clean diesels," will be subject to the same emissions restrictions as gasoline engines (tier-two emissions standards) thus making the concept of the "dirty" diesel a thing of the past.

Clean diesel technology will be achieved in two ways. For starters, beginning in June of this year, all diesel fuel sold in this country may contain no more than 15 ppm (parts per million) sulfur, compared with upward of 500 ppm that it used to contain. In addition, starting in January 2007, all new diesel cars and trucks sold in the U.S. will be required to have technology in place to reduce the smog-causing nitrous oxide (NOx) and particulate matter that escapes their tailpipes. According to EPA figures, once these standards take effect, 2.6 million tons of NOx along with 110,000 pounds of particulate matter will be eradicated each year.

While the new diesels will be as clean as their gas cousins, they offer a great many other benefits as well. Diesel fuel contains more energy than gasoline, which, in conjunction with the design and function of the engine, allows them to be much more efficient. The VW Lupo, a diesel-powered econocar sold in Europe, is rated at over 80 mpg. In 2000, two drivers took one on a 20,699-mile run and averaged 118 mpg at an average speed of 53.1 mph (Sure, they probably pulled out the seats to save weight, but hey, 118 mpg, right?).

On the sustainable front, diesels can be run on biodiesel and, with some modifications, used vegetable oil as well. This allows those of us who are interested in cleaning up our act to do something right now. And it's not just "greenies" doing this; the RallyVW team runs its cars exclusively on biodiesel. Earlier this year, an MIT study entitled "Vehicles and Fuels for 2020" found a diesel-electric hybrid to be on par with a hydrogen fuel cell-electric hybrid in terms of greenhouse gas emissions and total lifecycle energy use, which includes production, use and disposal (although it should be noted that pure electrics were not included in the study).

While the diesels of yesteryear were loud and sluggish, modern diesels are significantly quieter. (There's a reason why the TDI club sells license plate holders that read, "Yes, it's a diesel.") As for performance, they've come a long way in that department, too. Diesels have more low-end torque than an equivalent gasoline engine and many are turbocharged. Simply put, this allows you to jump off that starting line, or as VW touts, "It's what makes driving fun." Well, that and a really kickin' sound system.

In the coming years, expect to see new clean diesels from Audi, BMW, Honda, Mercedes, Nissan and VW, to name a few. Looking to the future, the possibility of diesel-electric hybrids, technology that is already in use in the mass-transit community, may offer even greater fuel-efficiency to the everyday driver.

So there you have it. Clean diesel technology, alternative fuel capability, accessibility and vroom. While the future of automotive transportation will hopefully be emissions-free, diesel is a great alternative that is here today, with even greater improvements on the way.