DETROIT — Forget all the jockeying behind saving General Motors and Chrysler for a minute and consider this: People are making do with the cars they have.

That leaves the automotive industry debating, and worrying, about what the new normal will be once the recession ends.

In recent years, Americans appeared to be hooked on the new-car smell and took advantage of home equity loans, easy credit and cheap short-term lease deals to send new-car sales to levels of more than 17 million a year.

Now, the market has collapsed by 46 percent to below 10 million.

Some say the downturn is temporary and that sales will spring back in a few years. Others believe Americans will rethink whether they need so many cars, particularly new ones.

The answer will be important to the Obama administration as it prepares to put GM into bankruptcy on Monday. After the company emerges from bankruptcy, the federal government will own about 70 percent of it, in return for $50 billion in taxpayer aid. GM has already received about $20 billion in federal help.

The Treasury Department’s advisers, who initially expected auto sales to pick up late next year, now foresee no jump in demand in 2009 or 2010. And even five years out, they expect annual sales to be about 15 million, still well below the peaks of this decade.

Making predictions is tricky. The market has grown more bleak, and worst-case scenarios drafted only months ago are becoming reality.

If sales do not recover, the Treasury will have to provide more financial support for GM and for Chrysler, which has received about $10 billion in federal aid, before they can stand on their own, and the government can divest its shares.

People like Kate Emminger do not offer the carmakers much hope. Emminger sold her 2006 Toyota Corolla last April because she decided she could not afford her $250 monthly payment, even though she earns about $60,000 a year. “It just became too expensive to have a car,” said Emminger, who now volunteers at City CarShare, a nonprofit organization in San Francisco, and earns the use of its vehicles, which normally rent to members for $5 an hour plus 40 cents a mile.

But plenty of people in Detroit argue that once the recession is over, buyers will rush back to dealer showrooms.

If sales do pick up, carmakers eventually could be more profitable than they have ever been because of all the costs they have shed, said David Cole, chairman of the Center for Automotive Research in Ann Arbor, Mich.

“After you rebound from this artificial low in demand, wow,” Cole said of the potential for auto sales and profits. He estimated that pent-up demand for new cars is actually about 4 million vehicles higher than the current selling rate, which in April would translate to 9.3 million a year, according to Autodata Inc.

Others, however, point to shifts suggesting that Americans’ desire — and need — for new cars may be cooling. Baby boomers, the biggest group in the car market, are beginning to enter retirement, a stage of life when people typically buy fewer cars. Home values are down sharply, making consumers feel less wealthy, and also cutting off a handy source of money from home-equity loans for new cars.

“We sold to people who purchased cars by refinancing their houses,” said Wilbur Ross, the billionaire financier who has invested in steel mills and auto parts companies.

The housing and financial crises have taken their toll on reliable customers like Frank Powell, who moved out of the East Palo Alto, Calif., house he had lived in since 1983 and started renting a few months ago because of his debt burden, which includes auto loans. “I used to buy cars all the time and took out loans to pay them off. As soon as I paid part of one off, I’d get another. I’d buy one for my kids, my wife, myself. I can’t do that anymore”

He now has a Cadillac Escalade sport utility vehicle, but he is thinking about downsizing and driving something much smaller — and for longer. “Something had to change. You just can’t keep going with that many cars.”

Lifestyles have changed, too. As people move back to cities from suburbs, they are swapping three-car garages for a single parking space. Public transit use is up.

“Too many people are looking at alternatives,” said Scott Griffith, chief executive of Zipcar, the national car-sharing company that has more than 300,000 members, up from about 200,000 a year ago. Griffith estimates that for every three members, a new car probably goes unsold. “They’re much smarter about spending money and looking for ways that don’t even involve cars any more.”

Donald Grimes, an economist at the University of Michigan, is forecasting the lowest sales for the driving-age population this year since 1970. From 1970 to 2001, there were 0.76 vehicle per driver in the United States. Now that figure has dropped to 0.4 vehicle per driver, and he does not see much of a rebound in coming years.

The swift decline has spooked the industry. “I don’t think there has ever been a period in our history like this,” Josephine Cooper, Toyota’s group vice president for government and industry affairs, said of her company, which lost $7.1 billion in the first three months of the year. “It is very, very sobering.”

No resolution for GM’s negotiations

General Motors Corp.’s board of directors met for a second day Saturday to make the final decision on whether the automaker would complete its restructuring by filing for bankruptcy protection Monday. The outcome of the meeting could not immediately be determined — GM and the Treasury Department, which has been guiding the Detroit automaker toward a rescue plan that will give taxpayers nearly a three-fourths stake in the company, went into secrecy mode. GM’s bondholders had a 5 p.m. Saturday deadline to accept an offer to swap their $27 billion in debt for at least a 10 percent stake in a new GM. Neither the Treasury Department nor GM commented on the deadline’s passing.

• What’s next: GM has yet to confirm it will seek bankruptcy protection, but it has scheduled a news conference Monday, when there’s a deadline to qualify for more aid.