"The average age of vehicles on the road is rising further and further," says an internal analysis by VW's sales planning and promotion department.
"Customers keep postponing the purchase of a new car to later dates for many different reasons," adds the report.
VW has launched a loyalty campaign that targets all its regular customers.
The second quarter campaign is aimed mainly at promoting the Golf lower-medium model.
The number of new registrations of Golf models dropped 5.2 percent in January and February from year-earlier levels.
Customers who trade in a Golf (except the GTI) older than 48 months will be offered a bonus of 2,000 euros.
A similar bonus of 1,000 euros is offered on the Golf Plus and a loyalty premium of 500 euros for the Touran minivan.
Martin Stangenberg, head of sales at VW Germany, cited Germany's weak economy as the main reason for the sales promotion.
With the campaign, he said, VW wants to honor "the long-term faith of its loyal customers."