The prospects of a white Christmas remain unclear, but we can report that this year's holiday will be a bit greener than usual. That's because the truck being used to haul the 2011 U.S. Capitol Christmas tree 4,500 miles from the Stanislaus National Forest in Northern California to Washington, D.C., features clean diesel technology.

The 65-foot white fir, which will be illuminated at the base of the Capitol building throughout the holiday season, is making its cross-country journey on a SmartWay-certified Mack Pinnacle Axle Back model sleeper that runs on ultra-low-sulfur diesel fuel and meets California's 2010 emission standards, which are the strictest in the country.

"The emissions from this truck are near zero, thanks to its more efficient engine and its new emissions control technology," said Allen Schaeffer, executive director of the Diesel Technology Forum. "It's as clean as a compressed natural gas truck."

The Diesel Technology Forum (DTF), a non-profit organization dedicated to raising awareness of the importance of diesel engines, fuel, and technology, is one of the national sponsors of the U.S. Christmas Tree Tour. DTF members Volvo Powertrain, Mack Trucks, and Robert Bosch LLC Diesel Systems North America also are sponsoring the tour.

The tree began its clean, green trek from California on Nov. 5 and will arrive in Washington on Nov. 28.