DETROIT – Last year, Hurricane Katrina – followed by Rita – socked the Gulf Coast, damaging the nation’s crude-oil infrastructure and sending gas prices spiraling.

The catastrophe took a bite out of auto sales – especially for big trucks – cooling off the hot employee-pricing craze of 2005.

From August through October last year, sales were down 21 percent at General Motors Corp. and 13 percent at Ford Motor Co. At the same time, sales rose only 2.1 percent at DaimlerChrysler AG.

Automakers release their monthly sales results for August on Friday. So the declines posted by GM and Ford last year might end up being a blessing for the automakers over the next few months – giving them easy year-over-year comparisons.

In August 2005, sales were down 13 percent at GM and up 6 percent at Ford. So GM will likely benefit this month; both should look better in September and October.

Robert Barry, an automotive analyst for Goldman Sachs, is predicting tepid August results for the industry overall and weak results for Detroit automakers. In a note to investors Monday, he said the softer spending “seems to be mostly driven by weak consumer confidence on the back of high gas prices, geopolitical risk, and weakness in housing” sales.

Despite a flurry of new incentives, including zero-percent financing for 72 months at Ford, Barry predicts a sales decline of 11 percent at Ford and 12 percent at the Chrysler Group.

“We expect GM sales to be flat, which is a poor showing” given its comparison to last year, Barry wrote.