General Motors Corp. said expanded rebates and other incentives helped boost its U.S. sales of cars and light trucks 6 percent in July over year-ago levels, its biggest sales gain this year.

Cross-town rival Chrysler Corp., meanwhile, on Friday reported a 9 percent sales decline for the same month - its sixth straight month of slower sales.

Among foreign automakers reporting Friday, Honda Motor Co. said its sales increased an impressive 32 percent on strong demand for its Accord and Civic cars. Toyota Motor Corp.’s U.S. sales grew 15 percent.

But it was GM’s strong showing that caught Wall Street analysts off guard, coming as it did after a dismal June performance that saw the automaker’s market share for that month fall to 28.4 percent.