WASHINGTON D.C. Parked along the street and marshaled by the reflecting pool in front of the U.S. Capitol building, they made for an impressive sight: a display of hybrid trucks and buses, some pulled from daily routes just that morning, meant to showcase their benefits to a wide variety of fleet operators.

Yet the hybrid trucks face a difficult hurdle. While hybrids remain ready and available for purchase by fleets, they cost significantly more than their diesel-only brethren -- and without higher sales volumes, the costs of hybrid trucks can't be driven lower.

"We're still in relatively low production mode and that means the cost structure for hybrids is still very high," said Dimitri Kazarinoff, gm-emerging technologies and business development for Eaton. "For that reason we need incentives -- incentives with real teeth, such as tax credits or rebates that will help drive up sales volumes for these [hybrid] trucks. Once we get higher volumes, we can get more of the cost out."

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WASHINGTON D.C. Parked along the street and marshaled by the reflecting pool in front of the U.S. Capitol building, they made for an impressive sight: a display of hybrid trucks and buses, some pulled from daily routes just that morning, meant to showcase their benefits to a wide variety of fleet operators.

Yet the hybrid trucks face a difficult hurdle. While hybrids remain ready and available for purchase by fleets, they cost significantly more than their diesel-only brethren -- and without higher sales volumes, the costs of hybrid trucks can't be driven lower.

"We're still in relatively low production mode and that means the cost structure for hybrids is still very high," said Dimitri Kazarinoff, gm-emerging technologies and business development for Eaton. "For that reason we need incentives -- incentives with real teeth, such as tax credits or rebates that will help drive up sales volumes for these [hybrid] trucks. Once we get higher volumes, we can get more of the cost out."

It's a theme echoed by other OEM representatives, fleet personnel, industry experts, and members of Congress attending the "Hybrids on the Hill" event June 11 in the nation's capital -- the need to generate higher sales volumes in the short term so the hybrid truck market can become "self sustaining" and survive in preparation for the day when fuel prices again rise significantly.

"We can really move the needle on fuel consumption and carbon emissions at the same time with hybrids," said Bill Van Amburg, senior vp at California-based Clean Transportation Technologies and Solutions (CalStart). "But right now, there are only 1,000 hybrid trucks on the road. We need higher volumes to get the price of hybrids down to where they become more affordable to fleets. If we can get sales up between 5,000 and 10,000 units a year, we'll be home free."

The key to hybrids now and in the future is that they offer large environmental benefits with significant cost savings as well for the fleet, said Victoria Mills, a staff expert with the Environmental Defense Fund.

"They can save 300 to 700 gallons of fuel annually, eliminate 100 tons of carbon dioxide produced over a typical truck's lifetime, cut soot emissions by 95% and reduce smog-causing emission by 25%," she said. "We're talking about multiple benefits from this technology in terms of human health, climate change, and energy security. That's why we support calls for incentives to help offset the higher price of hybrid trucks."

CalStart's Amburg believes most commercial hybrid trucks carry about twice the incremental cost that fleets can bear. "Fleets can bear some incremental cost for hybrids due to the benefits, such as fuel savings and reduced maintenance," he explained. "But there's a piece [of that incremental cost] that doesn't fit their business case."

John Formisano, vo-global vehicles at FedEx, said that if there's one thing to take away from the current discussions about hybrid trucks, it's that hybrids work. "They meet our [FedEx's] high reliability standards and have helped us reduce fuel consumption within our fleet by 13.5% -- a savings of 45 million gallons -- and are going to play a key role in helping our fleet improve its overall fuel economy 20% by 2020," he said.

"But we need to see production costs come down, as the cost for hybrids is still not where it needs to be," he said, noting that New York state now offers incentives that cover up to 80% of the incremental cost of hybrids for a wide variety of fleets, a program he believes the federal government should emulate.

"We know that the more companies that adopt hybrids into their fleets, the less they will cost all of us," Formisano added. "The proof of the benefits this technology offers is right in front us today."

Thomas Kelly III, senior vp-product portfolio management for Mack Trucks, noted that hybrids can even be a good fit for the rough-and-tumble operating environment of vocational fleets. "We think they'll work well as dump and refuse trucks, especially in stop-and-go environments where the truck works eight to 10 hours a day then returns to a central location every night," he said. "The higher torque/lower speed operating needs of vocational fleets dovetails nicely with the hybrid system's capabilities."

The greatest appeal of hybrids for fleets across the map, however, is going to be their cost-saving potential, said Chad Mitts, director of hybrids and new technology for ArvinMeritor, especially if fuel prices undergo a steep price spike again.

"It's a very simple formula -- hybrids save fuel and they save on component wear and tear," he told FleetOwner. The payback period is the difficult part, waiting for those accumulated savings to "pay" for the hybrid's higher sticker price, he says.

"Many variables affect that payback calculation, such as types of driving environment -- stop-and-go versus highway driving, for example -- and other conditions," Mitts said. "For our Class 8 hybrid tractor (built in partnership with Navistar) we're targeting a payback period of three years. Right now, it's about there, but we've got a roadmap to finally get us down to that three-year period. It'll take time and incentives, but the cost of fuel also affects that payback period heavily. A change in diesel prices can dramatically change the future of hybrids very quickly."