Out with the aluminum and in with composite material for a lighter truck and smaller engine. This truck, one of five being tested in different climates, also uses LED lighting to improve efficiency.

To green up its iconic brown delivery trucks, UPS is scrapping aluminum in favor of lightweight composite material.

The company last month began testing five delivery trucks built using a plastic-like material that reduces a truck's weight by about 1,000 pounds, or 10 percent. Although that may seem minor, it allows UPS to use a smaller, 4-cylinder diesel engine and get a projected 40 percent improvement in fuel efficiency.

The cost of the trucks is roughly the same, according to UPS executives. The material meets safety requirements and the strength of composite materials, which are widely used in aviation already, has improved greatly over the past ten years, they said. The main concern at this point is durability over time, said Dale Spencer, director of automotive engineering at UPS. The company essentially runs its trucks into the ground, expecting about 20 years of use until it costs more to maintain a truck than buy a new one.

UPS is investing in different types of alternative transportation, including hybrid, electric vehicles, propane and natural-gas trucks. Using lighter materials for fuel efficiency is a less-risky tactic in that it doesn't require changes in the fueling infrastructure.

The company made the jump to composite materials as part of its strategy to test new technologies and because fuel prices are high now. UPS has been investigating composite materials for years, but efforts in the past lost steam when fuel prices fell, Spencer said.

"We've all been on this roller coaster ride on the price of fuel. Every time we get excited to do a project like this, the price of fuel drops down to $2 and you lose your zip," he said. "But we've seen the writing on the wall [on fuel prices]...and we need to delve into alternative designs that are readily available."

The trucks, which are used for longer-haul deliveries rather than city routes, will use a standard Isuzu chassis, but most of the body will be composite material. The body is made by Utilimaster. UPS chose different climates, including Tucson, Ariz., and Albany, N.Y., to test the material.

In addition to being lightweight, the material, which Spencer said is mostly a type of thermoplastic called ABS, has some advantages. Less energy is used during the production process and no paints are needed, which is less polluting. If there's a scratch, it won't need to be painted over. In theory, UPS locations could keep panels on location and replace a damaged one, he added.

If the trucks don't last as long as hoped, Spencer said UPS can make repairs, rather than scrap the entire vehicle.

UPS doesn't expect its entire fleet of 70,000 trucks to convert to composite materials, but it's an available technology that can be used in conjunction with electric powertrains or alternative fuels, said Mike Britt, director of vehicle engineering at UPS.