New-car sales in western Europe fell by more than 15 percent in July.
Continuing weakness in Germany and a change in model year introductions in the French market were the decisive factors.
Germany continues to be plagued by large stocks of high-quality used cars, making new-car purchases less attractive.
Despite the strong performance of the German economy, potential new-car buyers are not excited by the models currently on offer, said an economist at one major European carmaker.
In France, a year-on-year fall of 36.2 percent was largely due to a change in the new-model year from July to June.
Economists expect a stronger third quarter in France will partly compensate for July's drop.
Other major markets were also down, but not as dramatically as France and Germany. The Belgian, Swedish and Irish markets continued to be strong in July.