SAN FRANCISCO -- A shaky economy and constricted credit market took a steep toll on September auto sales, with the industry rolling out numbers Wednesday every bit as gloomy as analysts had warned they would be.

Ford Motor Co. reported U.S. sales of its cars and light trucks plunged 34 percent last month compared with a year ago. General Motors Corp. sales fell 15.6 percent.

It was the 11th consecutive month of declining sales for the two carmakers, putting the industry on track for monthly domestic sales of fewer than a million vehicles for the first time since February 1993, according to Edmonds.com, a car-buying research site.

Weak results were not confined to Detroit. Among those reporting so far, Honda Motor Co. reported a 24 percent drop in U.S. sales, Hyundai Motor America sales fell 25 percent and Porsche AG sales tumbled 45 percent.

In addition to a weak economy, stubbornly high gasoline prices continued to cripple demand for larger vehicles. Ford said sales of its flagship F-series Ford pickups were down a staggering 41 percent from a year ago while sport utility vehicle sales tanked 57 percent.

"Consumers and businesses are in a very fragile place," said Jim Farley, a Ford vice president. "An already weak economy compounded by very tight credit conditions has created an atmosphere of caution."

The automaker said September marked its worst sales month so far this year and for the industry. At Ford, U.S. sales for September slumped to 120,788 vehicles from 184,612 in the year-earlier month. SUV sales plunged to 8,623 vehicle sales from 20,040.

Combined sales of Ford, Lincoln and Mercury fell 33.8 percent to 116,734 units, while Volvo sales slumped 51.8 percent to 4,054. Truck sales slid 39.5 percent to 76,281 units.

The sales decline is expected to force more car dealerships to close up shop as consumers grapple with surging food and gas-pump prices, and in some cases, home foreclosures.

On Wednesday, consulting firm Grant Thornton predicted 3,800 dealerships could go out of business, up from its earlier target of 2,700, as sales have plummeted and credit has dried up.

Bill Heard Enterprises, the No. 11 U.S. dealership, went bankrupt Sept. 24, closing 13 Chevy dealerships in Alabama, Florida, Georgia, Nevada, Tennessee and Texas. It also laid off most of its 3,200 employees. The dealer had once billed itself as "Mr. Big Volume."

Elsewhere in September:

Honda Motor Co. reported a 24 percent drop in U.S. sales to 96,626 vehicles in September from 127,200 units in September 2007. Total passenger car sales dropped 22.1 percent to 56,031 and truck sales declined 26.5 percent to 40,595.

"This September was an incredibly volatile month for Wall Street. Obviously, no one is immune to market shifts as dramatic as we have been seeing," Dick Colliver, head of American Honda, said in a statement accompanying the results.

Hyundai said it sold 24,765 vehicles, down from 33,214 a year ago. While sales of the company's Sonata model rose 31.7 percent to 8,629 vehicles, sales of the Elantra dropped 48.6 percent to 3,681 vehicles.

Porsche AG said sales fell to 1,458 vehicles from 2,641 last year. Sales of its 911 model fell to 516 vehicles from 989 last year, and Cayenne sales fell to 747 vehicles from 958 a year ago.

Daimler AG sold 20,557 vehicles, down from 22,459 a year ago. U.S. sales of Mercedes-Benz dropped 16.4 percent to 18,779 vehicles from 22,459 last year.

Daimler sold 1,778 Smart cars, which were not on the U.S. market a year ago.

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