Pictured is the new 2013 Passat in a bay at the Chattanooga Volkswagen plant.

Volkswagen Group of America reported Wednesday that Passat sales had their best August ever, with more than 43 percent of the Chattanooga-made sedans sold in the month sporting its clean diesel engine.

Jonathan Browning, the company's chief executive, said demand for the carmaker's diesel vehicles is "an underlying improvement in terms of consumer appreciation. We had a stellar month with our TDI clean diesels."

Despite strong Passat sales of 10,194 in August, overall VW U.S. sales in the month were down 1.6 percent from a year ago at 40,342 vehicles.

Still, the German automaker said August was only the third month in 40 years in which sales surpassed 40,000 units.

"Overall, we are pleased to see that demand for the brand remains strong," Browning said.

Concerning the overall market in the U.S., he said there are risks that the Syria situation and higher fuel prices may hurt consumer confidence.

But, Browning said, that people who feel secure in their jobs feel that it's a good time to buy a vehicle.

VW said that its Jetta compact recorded sales of 13,508 for August.