New-car sales in Maryland surged 28 percent in September, helping the state's automobile dealers post one of their best months ever, according to the most recent figures from the state's Motor Vehicle Administration.

Motorists, enticed by low-interest financing deals and rebates, bought 39,740 new cars and light trucks in September, nearly 8,700 more than they bought during September last year.

The last time more than 39,000 vehicles were sold in a month was in October last year, according to MVA figures.

Experts said the percentage gain was swollen because sales in September last year - which were 8 percent lower than those of a year earlier - reflected the dropoff that followed the terrorist attacks.

But new-vehicle sales in Maryland were better than those of the nation as a whole, which experienced a 5 percent decline.

Still, automobile sales nationwide have been strong for the year, said Paul Taylor, chief economist with the National Automobile Dealers Association, as automakers instituted rebates and low-cost financing to stimulate sales after the attacks.

"That longer historical view tells you that this is indeed a very strong year," Taylor said.

During the first nine months of the year, 312,082 new cars and light trucks, including pickups, vans and sport utility vehicles, were sold in Maryland, a 3.2 percent increase over the 302,284 new cars sold in the nine-month period last year.

"The same factors that have kept auto sales strong for much of this year remain in place, in particular the extraordinarily attractive financing options available to Maryland consumers," said Anirban Basu, director of applied economics of RESI, the consulting arm of Towson University.

"What distinguishes Maryland consumers from their national counterparts is that as a high-income state, our consumers are more likely to qualify for these deals," Basu said.

Basu warned of factors that could weigh heavily on the new-car market, including waning consumer confidence and a glut of used cars on the market because of trade-ins and expired leases.

"This is an emerging problem for new-car dealers ... and it may begin to manifest itself more strongly in the months ahead," Basu said. "This growth trend that we have seen will flatten out."

Charles McMillion, chief economist for Washington-based MBG Information Services, concurred that the automobile market has been strong in Maryland because of high personal income for several years.

"I've been expecting [the market] to weaken," he said. "But there continues to be terrific incentives and zero-financing options" for car buyers, he said.

John W. Miller, co-owner of a General Motors and a Ford dealership in Ellicott City, said September was "pretty good, not record-breaking" for his businesses. He said the month could have been better if he had more cars to sell.

But there are signs of a slowdown ahead.

Peter Kitzmiller, president of the Maryland New Car and Truck Dealers Association, which represents most of the state's 340 dealers, said sales slowed down considerably last month for Maryland car dealers.

"We have certainly done much better than a lot of the other sectors in the economy since Sept. 11," he said. "It seems to be softening a little now, but I think it has weathered it a little bit better."