General Motors Co.'s sales rose 6.4 percent in April as the auto industry continued to see signs of recovery, although the pace slowed from incentive-fueled March. GM said Monday that sales from its four remaining brands - Chevrolet, Buick, GMC and Cadillac - rose 20 percent. GM is phasing out or selling Saab, Saturn, Pontiac and Hummer. Sales fell 2.4 percent from March.