General Motors' decision this month to offer discounted four-year leases on nearly all its vehicles could push industrywide leasing to above 15 percent of sales this year.

That's higher than last year, but well short of the 20 percent to 25 percent seen in the late 1990s.

But buyers should beware: While leasing can provide lower monthly payments than a loan, many consumers are better off buying a car with today's discounted finance rates.

For one thing, at the end of the loan, you'll own the car. At the end of the lease, you'll own nothing.

And getting out of a lease -- because a job loss makes meeting the payments difficult or an unexpected baby makes a sports car impractical -- can be tough. You'll likely pay a stiff fee, if the leasing company will let you out at all.

But the biggest problem for those who lease might be overshooting the mileage restrictions. Most leases limit mileage to 12,000 a year. Turn in a car on a three-year lease with more than 36,000 miles, and you'll likely pay 20 cents a mile for the excess.

That was the problem Molly Fannin, 26, of Garfield, N.J., faced. A veteran of two earlier leases, Fannin found herself last summer already beyond the 36,000-mile limit on her Volkswagen Jetta a little more than two years into her three-year lease.

Fortunately for Fannin, Volkswagen bailed her out. Afraid that quality problems had irked too many customers, VW offered Fannin and thousands of other lease holders an early exit with no mileage penalties if they bought or leased another VW, something she was not planning to do.

"It was a good deal for me because of my mileage overrun, and saved me a lot," says Fannin, who now leases a VW GTI. Fannin, who put no money down on the GTI, has a monthly payment of $342. Had she bought the car with no money down, the monthly payment would have been $591 for a three-year loan at 1.9 percent interest or $370 for a five-year loan at 2.9 percent.

She got the lower monthly payment with no money down, but after three years, she won't have the car anymore. If she could have put 10 percent down on the new car, after six or seven years her annual cost of ownership would be far less than the lease.

And she has to watch her mileage again, something she vows to do. "It's going to be tough, but I don't want to be in that crunch again," she says.

"There are people who like the lower monthly payments that come with leasing," says Paul Ballew, head of sales analysis for GM. "And people who like the lifestyle of changing vehicles every three years without worrying about how much the trade-in is worth."