In January, the National Truck Equipment Association also conducted a survey of fleet owners. While 50% said they would buy more non-diesel trucks in the next year, 40% said they intend to buy trucks powered by compressed natural gas, 30% said they intend to buy trucks powered by electricity, and 26% said they intend to buy trucks powered by propane.

When available, fleets are doing more with smaller trucks and switching to gasoline. "The loss of power is a lesser evil than having to mess with the [diesel emission controls]," says Thad Pirtle, vice president and equipment manager for heavy-civil contractor Traylor Bros., Evansville, Ind. "We are making do."

Gruber says that while manufacturers are investing heavily in trucks and engines that run on alternative fuels, retail demand remains relatively low. "I think there is cautious optimism," says Gruber. "It comes down to anticipated quality. They want to see that it's proven out before they spend money."

Silver Lining

Although fleet owners operating heavy diesel trucks can expect to see higher maintenance costs in the near term, fuel economy is going up. The purchase price increase for EPA 2010-compliant clean-diesel trucks ranged from $6,000 to $8,000, J.D. Power says, but fuel economy rose to 4-5%. Heavy trucks now typically achieve 6.3 mpg, up from 6.0 mpg.

It may not seem like much, but "when you consider how many miles these people drive those trucks, that absolutely is the silver lining," Gruber says. Also, routine maintenance items, such as oil-change intervals, improved, stretching out, on average, to 22,703 miles from 20,303 miles the prior year.