Marines and sailors with the 24th Marine Expeditionary Unit drive Humvees toward Jordan after offloading from the USNS Sgt. William R. Button, a Maritime Prepositioning Fleet ship, on May 7, 2012.

WASHINGTON — For sale: military Humvee in jungle green or desert tan. Great for hauling cargo, artillery and soldiers. Can ford rivers, traverse sand dunes and bound over rocky terrain. Not recommended for heavy urban combat or mine-laden roads.

Bidding starts at $7,500.

After a storied career that spanned the 1991 Persian Gulf War, Bosnia, and the wars in Iraq and Afghanistan, the United States' fleet of Humvees is entering its twilight and are being sold to the highest bidder by the dozen. It is an icon of the U.S. military that replaced the Jeep and spawned a gas-guzzling commercial cousin that symbolized American ego and extravagance.

But now the Army wants a tougher, yet nimble vehicle, light enough so that a helicopter could fly it around, but resilient enough to withstand bomb blasts.

In one of the most important — and lucrative — contracts awarded by the Army in years, three major defense firms are competing for the $30 billion prize to build 55,000 vehicles, called the Joint Light Tactical Vehicle, which would debut as one of the military's most high-profile vehicles in a generation.

Wars are often measured by the box-score statistics — battles won and lost, us-vs.-them casualties, cities sacked, shorelines held. But they are also defined by their arsenals — just as the rumble of a Sherman tank was the soundtrack of World War II, so too was the riff of Huey chopper blades in Vietnam.

And now comes a new entrant to the symphonic cacophony of the Next War — the mad-scientist mating of a Jeep with a tank. After a decade in development, the Pentagon is about to unveil the JLTV, designed for front-line combat as well as ferrying supplies behind the wire.

The JLTV would be another branch in a family tree that includes the Jeep and the Humvee, which both served with distinction, from the Ardennes forest to the sands of Anbar province. And both produced commercial offspring that quickly became embedded in the American cultural consciousness.

The Humvee entered the commercial market in large part thanks to the Terminator himself, Arnold Schwarzenegger, who wanted a muscle commando vehicle for his personal use, and pushed AM General, the manufacturer, to produce a civilian version.

"Look at those deltoids; look at those calves," he once reportedly said while admiring a Humvee.

For a time, the American public was also enamored with its brawny excess. Sports stars, rappers and celebrities owned them. Paris Hilton had a black one but said she really wanted one in pink. Dennis Rodman's Hummer had naked ladies painted all over it. Hugh Hefner's Playboy went for a stretch limo Hummer with a leopard-skin print interior and mirrors on the ceiling.

But while the Jeep endures as a symbol of reliable sporty ruggedness, the Hummer, controversial from its commercial inception, was derided for its size and low miles per gallon. Environmentalists howled, and even burned down a dealership in California.

The production line folded, and the last new Hummer was sold in 2010 a decade after General Motors acquired the brand.

"Everything it stood for just kind of collapsed," said Jessica Caldwell, director of industry analysis at Edmunds, the online car industry site. "It was seen as completely frivolous and ultimately that led to its demise. It's not cool to have a car that gets 10 miles to the gallon."

The Humvee made its military debut in the 1980s, served in the Gulf War and soon became "a ubiquitous symbol of the American military," said Joseph Trevithick, a fellow at globalsecurity.org, a military research institution.

Over the past 30 years, AM General has produced more than 300,000 Humvees for 60 countries. It recently inked hundreds of millions of dollars in sales to foreign governments including Afghanistan, Kenya and Mexico.

The United States has more than 160,000 in its fleet. In addition to the vehicle's service abroad, the National Guard has deployed it to respond to hurricanes and floods domestically.

"It sends a very strong message to citizens that when they see soldiers coming in Humvees, the cavalry has arrived," Maj. Gen. Emmett R. Titshaw Jr., the former adjutant general of the Florida National Guard, recently told National Guard Magazine.

In Iraq, the Humvee's vulnerability also came to symbolize a botched occupation in which the military and its leadership were not prepared for the long slog — or how the insurgency eliminated traditional battle lines.

As the conflict dragged on, the military wore out its tanks and other armored vehicles and had to rely on Humvees for combat patrols — something for which they were not designed.

Facing an enemy that relied on hidden roadside bombs, U.S. casualties mounted, especially for forces travelling in unprotected Humvees. Soldiers used what they called "hillbilly armor" to fortify their vehicles, finding armor in scrap yards and bolting it to their Humvees.

One Army unit dubbed its Humvee "Rocinante" after Don Quixote's horse, a symbol of obsolescence.

In 2004, Spec. Thomas Wilson, a soldier with the Tennessee National Guard, asked Defense Secretary Donald H. Rumsfeld about it, saying flatly that "our vehicles are not armored."

"We're digging pieces of rusted scrap metal and compromised ballistic glass that's already been shot up, dropped, busted," he said, "picking out the best of this scrap to put on our vehicles to take into combat."

Rumsfeld's now-famous response: "You go to the war with the Army you have."

The Pentagon moved quickly to armor the Humvees and to procure much more heavily armored Mine-Resistant Ambush Protected vehicles by the thousands. But behind the scenes they were already planning the next-generation vehicle, now known as the JLTV.

It is supposed to be as mobile as an unarmored Humvee, an able off-roader but also powerful enough to withstand the same blasts as the MRAP — all while hauling plenty of cargo.

The bidding has attracted three defense giants for the contract, which is expected to be awarded this summer: AM General, which built the Humvee; Oshkosh, which built the MRAP; and Lockheed Martin, the world's largest defense contractor.

Though known primarily for its aerospace business — Lockheed makes the F-35 Joint Strike Fighter — the Bethesda, Maryland-based company was drawn to the competition because it "was viewed as a particularly challenging engineering proposition," said Scott Greene, vice president of the ground vehicles division. The goal, he said, is to "bring the properties of the different vehicles and combine those attributes into a much smaller package."

The new vehicles, which the Marine Corps will buy in much smaller numbers, won't entirely replace the Humvee, which will remain in the fleet for years to come. But much of the fleet is old and in need of repair. And every week IronPlanet, which holds online auctions, sells about 50 Humvees under a Pentagon contract. About 75 percent of the proceeds go to the Defense Department.

The buyers are ranchers and farmers, and car and military enthusiasts, who want to own a piece of history.

"The demand is very high," said Jeff Holmes, IronPlanet's vice president of government solutions. Some auctions pit a dozen bidders against one another, driving up the price, he said.

Craig Pezold, a college student who lives in Jessup, Maryland, recently bought one for $10,000. He tinkers with it in his father's garage and takes it off-roading around the farm.

"It'll go through the woods pretty good," he said. But it's confined there because, as he said with a sigh, "it's not road legal."

