Cascadia 113 CNG daycab tractor, equipped with a Cummins Westport ISX12-G engine

LONG BEACH, CA. — Freightliner Trucks and Westport Innovations are in the midst of cross-country U.S. trips running compressed natural gas-powered trucks to prove the availability of the fuel out on the road.

The trips are meant to show that a CNG infrastructure is rapidly developing, and that long-haul runs on CNG are feasible.

Freightliner is running a Cascadia 113 CNG daycab tractor, equipped with a Cummins Westport ISX12-G engine, and pulling a 53-foot trailer carrying a 30,000-pound load, the company said.

The trip started in Long Beach, Calif., on May 17th and will wrap up in Washington, D.C., on the 24th.

Westport Innovations has a team driving a new Ford F-250 equipped with a WiNG bi-fuel system from Plymouth, Mich., to New York. The Ford can run on CNG or gas.

Freightliner wants to prove that a truck, with a little planning, can run on natural gas coast-to-coast.

"These days, CNG at the pump is about half the price of diesel or gasoline," said a Westport spokesperson in a statement.

"While there are currently fewer natural gas fueling stations than traditional gas stations, the numbers are growing and with planning, it's possible to do a long-haul trip entirely on natural gas."

Freightliner set up a dedicated website where you can follow their progress, read the driver's blogs, and see how much money is saved on fuel (you can also enter a contest to win an iPad). You can check it out here.

There are also making stops along the way for scheduled ride and drives, natural gas education, as well as some giveaways.