The Hummer brand is under review and could be sold or revamped, according to Rick Wagoner, CEO of General Motors Corp.

Wagoner, in comments before the opening Tuesday morning of the GM shareholders meeting in Wilmington, Del., revealed possible changes for Hummer.

Wagoner also announced that four GM truck and SUV plants in the U.S., Canada and Mexico will be closed because of surging fuel prices.

The Hummer H2, the brand’s largest SUV, is produced in Mishawaka by AM General Corp.

Wagoner’s comments raise questions about the long-term outlook for the Mishawaka plant, where about 400 workers returned to their jobs Monday after a three-month layoff resulting from a parts supplier strike.

“That’s the nature of the beast,” said H2 employee Dennis Cox. “We'll continue to build quality trucks here with GM; if not GM, we’ll build them for somebody else."

"With the economy the way it is, things are going to happen,” said employee Richard Rittenhouse, Jr. “In the past, AM General has always had jobs. Whether we sell out the Hummer name or not we’ll have something here.”

Joanne Krell, a spokeswoman for GM in Detroit, said the "strategic review" for Hummer reflects changes in the auto market where consumers are turning to smaller, fuel-efficient cars instead of trucks and SUVs.

Comments about the results of that review at this point would only be speculation, she said.

"We know this brand has great potential," Krell said. "It’s an excellent brand, an iconic brand."

The strike by the United Auto Workers against American Axle and Manufacturing Holdings Inc. also forced GM to shut down several truck and SUV plants this spring.

The H2 is based on a GM chassis but was inspired by the Humvee, a military vehicle produced by AM General in an adjacent plant.

Under a deal with GM, AM General builds the H2 but GM owns the Hummer brand. H2 production started nearly six years ago in the summer of 2002.

A civilian version of the military Humvee, called the Hummer H1, was sold by GM for several years but has since been phased out.

The H2 is powered by a large V-8 engine. Because of the vehicle’s size, the H2 doesn’t have an EPA fuel economy estimate.

The mid-size Hummer H3 is produced in a GM truck plant in Shreveport, La. The H3 has smaller V-8 and five-cylinder engines.

Krell said there are no plans to change the H2 and H3 powertrains in an effort to improve fuel economy. She noted that the H2 engine is capable of running on E85, a blend of 85 percent ethanol and 15 percent gasoline.

Plans for the H3T, a pickup truck version of the H3, still are on schedule, she said.

She said there are no announced plans for the Hummer HX, a concept displayed at auto shows that would be smaller than the H3.