Price increases at the pump have pushed sales of large vehicles into decline, but some industries such as construction and utilities need payload and towing capabilities that big vehicles offer.

Responding to these needs, Provo-based Raser Technologies Inc. is working to develop technology to extend the gas mileage of light trucks and sport utility vehicles to as much as 140 miles per gallon in city driving. The vehicles also would have near-zero emissions, the company said.

Using a 200-kilowatt electric motor and lithium batteries, Raser and its partner, German company FEV Inc., expect the hybrid trucks to be capable of going up to 40 miles powered by the electric battery. After that limit has been exceeded, the truck would start generating its own electricity from the gasoline-powered motor and would be able to travel another 400 miles, said Raser Vice President David West.

"Vehicles are called on for a number of duties, and because of oil prices people are having to decide between payload and fuel economy," he said. "But a 4-by-8 piece of plywood won't fit on a Prius."

Sales have been dismal in recent months for gas-guzzling SUVs, trucks and some minivans. General Motors Corp. closed four pickup-truck and SUV factories in June, reducing its ability to produce pickups and large SUVs by about 35 percent. Ford this week said it plans to convert three large-truck and SUV plants to small-car factories.

Chrysler's U.S. sales fell 22 percent in the first six months of this year as customers shunned its trucks and SUVs in favor of smaller, more fuel-efficient cars. Industrywide, U.S. sales were down 10 percent, but the decline hit Chrysler harder because trucks and SUVs make up 72 percent of the company's U.S. sales.

Yet Americans are used to the recreational and working lifestyle that large vehicles allow, said Richard Putnam, Raser's director of investor relations and treasurer. Larger vehicles can tow boats and recreational vehicles and fit a full family comfortably, features which historically have helped make them big sellers, he said.

Raser is currently developing two prototypes of plug-in SUVs that have been purchased by the California utility Pacific Gas and Electric Co. Putnam estimated that the vehicles would be available by the end of the year for the utility to test.

Andrew Tang, a senior director at Pacific Gas and Electric, said the utility has one of the largest fleets in the nation.

"Plug-in hybrid electrics present tremendous potential to reduce the environmental impact of our operations and fuel costs," he said.

West said Raser expects its plug-in hybrid trucks to cut operational costs for large fleets by as much as 75 percent by driving in all-electric mode during a fleet's typical daily route of roughly 40 miles.

San Francisco-based Pacific Gas and Electric has more than 12,000 vehicles, many of which are light trucks or SUVs, according to Efrain Ornelas, an environmental technology supervisor for Pacific Gas and Electric. The utility already has 1,400 vehicles in its fleet that run on alternative fuel sources such as natural gas and hybrid technologies.

"Many of our fleet trucks are driving in urban environments, and the 40-mile capacity of the plug-in hybrids fits in perfectly with our needs," Ornelas said. "Some of our routes wouldn't require the trucks to ever use fuel, and others may only use small amounts."

In a state where diesel fuel is hovering above $5 per gallon, Ornelas said, the ability to pay less than $1 to charge the electric vehicles could make a significant dent in the utility's operation costs.

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