The industry sold 139,977 certified used cars and light trucks in July, 4.1 percent more than in July 2003.
Certified used-vehicle sales from January though July totaled 924,558 vehicles, 5.0 percent more than in the year-ago period.
General Motors' GM Certified program remains the top seller. It sold 38,940 certified used cars and light trucks in July, up 11.5 percent over July 2003.
That performance surpassed GM Certified's previous monthly sales record of 37,724 vehicles in March.
The GM Certified brand includes Buick, Chevrolet, GMC, Oldsmobile and Pontiac. Cadillac, Saab and Saturn have separate programs.
The Volkswagen unit of Volkswagen of America Inc. showed impressive year-over-year percentage gains. It introduced a marketing program this year.
Volkswagen sold 4,762 certified used vehicles in July, 32.6 percent more than it sold in July 2003. It sold 32,629 in January through July.
That was a 44.6 percent increase over the first seven months of last year.
Nissan Division of Nissan North America Inc. sold 3,870 certified used vehicles in July, exceeding its year-ago sales by 16.9 percent.
The company sold 24,133 certified used vehicles in the first seven months of 2004, a 27.0 percent increase over the year-ago period.
But certified used vehicles sales at Infiniti, Nissan's luxury division, plummeted. The division overhauled its certified used-vehicle program this year.
Infiniti sold just 212 certified used vehicles in July, a 57.6 percent decline from its July 2003 sales.
The company sold 2,482 certified used vehicles in the first seven months of this year.
That was an 18.4 percent decline from the year-ago period.
BMW, the largest seller of certified used luxury vehicles, sold 6,550 vehicles in July.
That was a 12.3 percent increase over July 2003.
BMW sold a 42,405 certified used vehicles in the first seven months of 2004, up 7.6 percent over the year-ago period.