DETROIT - Fleet sales provided 38 percent of General Motors' May sales, with a 45-percent increase to 83,305 vehicles.

Steve Carlisle, vice president for U.S. sales, said fleet sales will account for 25-percent of overall sales by year-end, according to The Street. 

Total GM sales for the month of May was 223,882 vehicles, a 17-percent improvement.

The automaker said combined sales of the four core brands - Chevrolet, Buick, GMC, and Cadillac - posted a double-digit sales gain for the fifth straight month. Sales of its four surviving core brands went up 32 percent, reported the Street.