DETROIT (WKZO) --  July sales at General Motors fell by over six-percent compared to the same period last year.

The automaker says the decline was due to a 41-percent drop in rental fleet sales.  GM said in July that rental sales would be lower because deliveries of those vehicles happened sooner this year than in 2011.

GM did report a strong increase in sales of the Cadillac brand which was up by nearly 21-percent.  However all other divisions, including Chevrolet, Buick and GMC, showed a decline in sales in July.