Call me a sucker, but I honestly came away from the North American International Auto Show believing some of the most talented minds in the industry are taking this Partnership for a New Generation Vehicle (PNGV) business quite seriously.

General Motors Corp. is ready to put a second-generation nickel-metal-hydride battery in the EV1. Ford Motor Co. has taken enough weight out of the P2000 to reach 63 mpg (3.73L/100 km) with a lean 1.2L 4-cyl. engine. Chrysler has a diesel-electric hybrid that can propel a plastic-body Intrepid 70 miles (3.44L/100km) on a gallon of diesel fuel. Toyota is upping production for its Prius electric/gasoline hybrid. And just about everyone is going ga-ga over the fuel cell advances coming out of this Ballard outfit in Vancouver, BC (see story, p.75).

There's only one problem: diesel engines. Carol Browner and her clean air cops at the U.S. Environmental Protection Agency have made it very hard for the largest automotive market in the world to accept them.

The National Ambient Air Quality regulations, which will take effect early in the 21st century, are especially strict on particulates, those microscopic specks of soot that diesel exhaust throws into the air, although in considerably lower concentrations than a decade ago.

But diesels, it turns out, may be the key to PNGV's mission.

We're talking about an evolution. We won't go from 5.9L V-8's muscling massive sport/utilities at 15 mpg (15.7 L/100 km) to environmentally pure fuel cells overnight. To get there from here, we will need diesels.

"We could use something else, but the direct-injection diesel is really the one that started getting us to the fuel-efficiency we were looking for," says Chrysler Corp. Executive Vice President Thomas C. Gale, speaking about the Dodge Intrepid ESX2, Chrysler's most recent tangible prototype derived from its PNGV-backed research.

Look at the sequence of GM's advanced propulsion strategy. First comes a nickel-metal hydride battery for EV1 and the S-10 electric truck. Then comes a series hybrid, featuring an electric motor charged by the world's most efficient gas-turbine generator.

We're talking 60 mpg (3.9 L/100 km) on reformulated gasoline, 0 to 60 mph (0 to 96 km/h) acceleration of 9 seconds and a combined battery-turbine range of 350 miles (560 km).

Yet to reach the next level, which GM defines as 80 mpg (2.9 L/100 km), a range of 550 miles (880 km) and 0 to 60 acceleration of 7 seconds, it will take a direct-injection diesel.

Kenneth R. Baker, vice president of GM's global research and development operations, says Amoco is working with the world's largest automaker to develop lower-sulfur forms of gasoline and purer grades of diesel fuel that would generate fewer particulates and less nitrous oxide.

But unless there's a more forgiving regulatory attitude toward diesel engines, there's no way to achieve the type of fuel economy levels that could make a difference in slowing the increase of CO2 emissions.

Sure we can achieve some fuel- economy improve-ment from hybrids based on direct-injection

gasoline engines. One can argue that with gasoline prices expected to remain flat or even fall over the next two decades, which is the outlook of the Energy Information Administration, 50 to 60 mpg would be good enough.

Maybe. Still it's unclear whether the current regulatory agenda will accommodate such a compromise.

"Even direct-injection gasoline engines can put out high enough levels of particulates that they would not comply with recently enacted air quality standards," says John H. Johnson, professor of mechanical engineering at Michigan Technical University in Houghton, MI. Mr. Johnson has served as senior consultant to the National Academy of Sciences Diesel Impact Study Committee.

Sooner or later environmentalists and politicians are going to have to acknowledge the trade-off between our current obsession with eliminating all hydrocarbon emissions and any credible attempt to reduce greenhouse gases.

It's wonderful that everyone and their uncles are thumping their chests about 1998 models certified to meet California's Low-Emission Vehicle threshold in advance. But stacking one catalytic converter on top of another does nothing to improve fuel economy. One could argue that as these super-clean LEVs, or even Ultra Low Emission Vehicles, begin to filter into our commuting fleets, motorists might start driving more miles per year. Hey, we're doing our part, we'll smugly assume. The poster in the dealership says I'm driving the cleanest car on the road.

Indeed, the air will be cleaner, but our CO2 levels will continue to rise.

Maybe it doesn't matter. For most of us global warming is either a hoax or some abstract scientific problem that won't wreak serious havoc in our life time.

But if there ever is a global consensus about containing greenhouse gases, how will the U.S. ever convince countries like China and Brazil that they need to sign on, when we effectively outlaw the very technology that can get the job done?

And if we block the evolution of diesels, the commercial viability of fuel cells - which may solve both the hydrocarbon and CO2 dilemmas - may be something the industry is still dreaming about at the North American International Auto Show of 2020.