But the total number of private new-car sales in Germany fell by 1.9 percent in 2004, according to the latest results from the market research institute Dataforce.
Market leader Volkswagen increased unit sales within the fleet sector by almost 12 percent compared with the previous year, pushing the company's market share to around 25 percent.
BMW is the second largest fleet supplier, with a 13.9 percent market share. A volume increase of 26 percent meant that BMW enjoyed the highest growth of any German manufacturer during 2004.
"BMW managed to increase unit sales for almost all their models. On the other hand, Mercedes-Benz is the only German brand that lost out in 2004," said Dataforce managing director Angela Boehm.
Audi increased its fleet sales by 3.7 percent to achieve a 12 percent market share. Audi took third place in the fleet-sales rankings from Mercedes, whose unit sales fell by 2.5 percent.
The growth was in contrast to 2003, when German brands suffered a decline in unit sales.
Volvo showed the highest volume increase within the fleet-sales market. The Swedish automaker increased sales by 38.1 percent compared with 2003, when it under-performed.
"The comeback is solely due to the V50, which now sells almost as strongly as the V70," said Dataforce's Boehm.
Skoda (up 31.7 percent), Peugeot (14.4) and Mazda (14.1) all gained in fleet market share during 2004, while Renault remains the strongest imported brand in Germany, with a market share of 4.2 percent -- despite an 8.4 percent drop in volume.
Last year's biggest losers were Saab (minus 14.8 percent), Lancia (12.0) and Citroen (10.5).
Margins within the fleet market are significantly lower than in the private market.
The private market continues to decline, with private owners now keeping their cars for an average of eight years, compared to the standard three-year replacement cycle for fleet cars, according to Dataforce, a market research institute that has specialized in tracking the German fleet market since 1997, in cooperation with the German Federal Motor Vehicle Registration Agency.
In 2004, Volkswagen's Passat was once again the biggest-selling fleet car, followed by the VW Golf, Audi A4, BMW 3 series, BMW 5 series, Audi A6, Mercedes-Benz E class, VW Touran, Mercedes C class, and the Opel Astra.
January new-car sales in Germany declined by 3.7 percent compared with December, according to the German Federal Motor Vehicle Registration Agency.
Private new-car sales fell 8.8 percent. Fleet sales were down 0.2 percent.
The following brands showed a strong performance in January: Honda (up 89 percent), Peugeot (32 percent), Volvo (31 percent), Nissan (28 percent), Citroen (25 percent). Opel and Audi both gained 18 percent.