Some odd vehicles could be seen making their way around San Francisco earlier this fall. More than 100 cars, trucks and buses gathered there for the Challenge Bibendum, an annual competition to test environmentally friendly vehicles. Gasoline-powered vehicles were in short supply, with the trucks, cars and buses showcased getting their energy from diesel, electric, bio-fuel, hydrogen, natural gas and liquid petroleum gas.

This was the first time in the five years of the event that heavy-duty vehicles took part in the three-day competition, which pits different advanced technologies head-to-head, rating them on emissions, acceleration, braking, noise and energy efficiency.

"We have made an important start in integrating commercial heavy-duty vehicles into the competition," said Patrick Oliva, director of the Bibendum Challenge. "It is a crucial component of road mobility and an area in which environmental technologies are quickly emerging."

Eleven organizations, including truck companies, universities, car makers and the Environmental Protection Agency, showed off their advanced technology in the Bibendum, which was started by Michelin. Bibendum is the name of the Michelin Man, the French tire maker's logo.

Volvo Trucks of North America received high marks in the overnight idling competition, where it entered its 2003 VN780. Freightliner showed a 1999 LLC Century S/T with a fuel cell auxiliary power unit that also performed well in the idling category.

Other heavy-duty vehicles that took part in the competition:

• Eaton showed a pick-up and delivery truck with a hybrid electric engine.
• The EPA showed a Ford F550 diesel/electric hypbrid prototype.
• Georgetown University presented a RTS Nova bus with exotic fuel and propulsion systems. The bus was powered by hythane, a mixutre of hydrogen and methane.
• GM Allison showed a 40-foot hybrid electric bus.
• Harris Ranch Feeding Company tested a three-axle Freightliner Century Class Day Cab with internal combustion engine fueled by liquid natural gas.
• Isuzu Truck introduced a single-fuel direct-injection diesel-cycle CNG truck prototype, powered by a 4.5 liter engine.
• The Napa Valley School District showed a Blue Bird school bus with an electric engine.
• Norcal/Cummins Westport featured a Peterbilt 385 tractor with a hybrid propulsion system powered by gaseous hydrogen.
• PG&E showed a Freightliner FL70 tractor with John Deere CNG-fueled engine.