The vehicles, to be deployed this year in the western US, will replace older generation diesel vehicles.

These LNGs are expected to produce 25% fewer greenhouse gas emissions compared to the older trucks and use 95% less diesel fuel than the vehicles they replace.

The LNG tractors are powered by Westport HD Systems and initially will pull trailers on a transit lane linking Ontario, California, and Las Vegas, Nevada, along with UPS’s 11 existing LNG tractors.

LNG technology uses natural gas as the main fuel with a small amount of diesel delivered at high pressure to the combustion chamber.

UPS is working with the DOE’s Clean Cities program to construct a LNG fueling station in Las Vegas.

Once that facility is completed in 2011, UPS will base the 48 new tractors in Las Vegas and expand the number of long-haul routes in the West on which they’re used.