In response, auto manufacturers are working to develop special after-treatment systems for diesel exhaust. Peugeot, for instance, has introduced a particulate trap. Enabled by the common rail system, the device captures the soot particles produced by the engine and burns them to levels low enough to be practically unmeasurable, according to Peugeot. Ford, meanwhile, has developed a system in which a solution of urea, an ammonia-based compound, is held in a tank on the car. The urea, which is injected into the exhaust gases before they have finished their progression through the catalytic converter, eliminates most of the nitrogen oxides. Ford has built a research vehicle equipped with a particulate trap and the urea catalyst that it asserts meets California's stringent new standards.
Troublesome emissions aren't the only remaining obstacle, however. For one thing, whereas in Europe diesel fuel -- often subsidized by governments -- is generally cheaper than gasoline and readily available, here gas is cheaper and diesel hard to find. A second hurdle is that diesel engines cost more to manufacture than gasoline engines, in part because they require extra equipment such as the particulate traps and urea scrubbers. Unless U.S. officials institute tax breaks like the ones available in Europe, those higher prices will be prohibitive.
At this point, in fact, diesel experts assert that the political challenges are more daunting than the technological ones. I recently test drove the Volkswagen Golf to evaluate the new diesel technology, and I had to agree. The experience vividly demonstrated how far diesel engines have come since the days when I had to coax my Rabbit to start up on a cold day. Nothing about the Golf indicated to me that it was a diesel, other than the diesel fuel label on the fuel tank -- and the long distances I could travel between fill-ups.
Diesel Roars in the Baja 1000
Ojos Negros, Mexico -- It's mile 127 of the Baja 1000, the world's oldest and most prestigious off-road race, and the 8,100-pound Ford Excursion I'm strapped into takes to the air, stretches its full 16 inches of suspension -- and lands surprisingly gently on 37-inch wheels. Even more astonishing than the soft landing, however, is the fact that this behemoth is diesel-powered-living proof that diesel engines can match the power of their high-performance gas brethren and thereby appeal to more than the fuel-economy minded.
Racing veteran Steve Scaroni of SMD Motorsports transformed this full-sized SUV, originally designed for the Sunday mall crawl, into a dune buggy on steroids. The truck is equipped with a 60-gallon fuel tank with a firewall, off-road coolers that double the capacity of the radiator, and a so-called intercooler, made by Hypermax, which ensures that air from the turbocharger gets cooled before it reaches the engine. Other modifications include a larger turbocharger and a special fuel injector, co-developed by International Truck and Engine Corp. and Caterpillar for marine applications, that yields a 15 percent boost in flow capacity.
This monster went like spit across desert-dry lake beds, over pine-forested mountains, and through cactus fields in the November 2001 race. And no wonder: Its 7.3-liter turbocharged Power Stroke engine, made by International, pulls 400 horses and 850 pound-feet of torque from V8 stock that normally produces 235 hp and 505 lb.-ft. of torque (granted, the emissions are nasty).
The race ended early for us -- in a cactus bed filled with boulders -- courtesy of a steering box that clearly needs to be upgraded before next year's event. But the Excursion accomplished its larger mission: It proved that diesel is a contender.
> Sue Mead
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.