Maybe General Motors should throw in a fleet of Cadillacs.

The automaker is dumping its corporate jets into what some participants say is the worst market they have ever seen.

Just seven months ago, hundreds of mega-millionaires, including Ralph Lauren and David Geffen, were elbowing one another in the lineup to buy a $60 million Gulfstream 650, which was not expected to hit runways until 2012.

It did not matter that $500,000 had to be wired to Gulfstream’s account at a Midwest branch of JPMorgan Chase at exactly 12:01 a.m. April 15, or that bidders who secured a place in the waiting line could not sell their rights if they changed their minds, according to one bidder.

Some eager moguls even tried to improve their chances of getting a jet quicker by opening accounts at Chase’s Midwest office. Among high-ticket status symbols, “me and my brand-new jet” was it.

But that was another era, before the credit crisis and before billions of dollars in corporate and individual wealth were lost.

“The jet market stinks,” said Richard Santulli, the chief executive of Netjets, the private jet company owned by Berkshire Hathaway, the holding company of Warren Buffett.

To control costs, companies including Citigroup and Time Warner are selling their jets. Alcatel-Lucent has allowed leases on two jets to expire, without renewing them, and has put its third jet up for sale.

And the public relations fiasco that engulfed the chief executives of Detroit’s auto-makers when they flew to Washington on company planes to seek a government bailout has underscored how inappropriate such travel can seem in this recession.

General Motors, which leases seven planes, put the majority on the market before the government said it must do so as a condition of government assistance. The automaker has also closed its air transportation services unit, which had 49 employees.

“We could not justify an in-house aircraft operation,” a GM spokesman, Tom Wilkinson, said. “We are negotiating to transfer the remaining planes to another operator. Ford too has shut down its flight department.”

Among jets, the large-cabin, long-range segment of the market is suffering the most, said Bill Quinn, the director of aircraft sales and acquisitions at Cerretani Aviation, based in Boulder, Colo. That includes planes from Gulfstream, Bombardier and Falcon.

Carrying costs are high. A Gulfstream 550 costs about $47 million. Although expenses can vary by state, one mogul’s business manager estimated that annual costs run about $1.3 million, including $500,000 for property tax and $400,000 for pilots and stewards. Typical operating costs are more than $2,000 an hour in the air, he said.