Suzuki's German dealers sold 20,408 cars by the end of October, almost 300 units less than during the same period in 2003.
Last year Suzuki sold 24,500 cars in Germany.
Suzuki sales boss Thomas Wysocki said he is worried that Suzuki's regular customers are growing older. The brand, which was first launched on the German market 25 years ago, needs new and young customers, he said.
Suzuki's new "20 plus" marketing campaign is aimed at attracting customers over 20, said marketing director Guido Hannich.
Suzuki hopes that its new campaign will help it win around 12,000 new customers by 2006.
The importer also is expanding its sales network. Suzuki currently has 390 sales partners in Germany, but this total is set to grow to 550 by the end of 2006.
Joachim Getz, who is responsible for the development of the Suzuki dealer network, said he believes that urban areas in particular have the potential for new locations.
Being a "friend of multi-brand dealers," he believes that Suzuki would be a perfect add-on for Toyota or Mitsubishi.
Currently a Suzuki dealer sells 72 vehicles a year on average. Getz said the number should rise to at least 80 units by the end of 2006.