The Audi A4 DTM
A completely new car was developed at Audi Sport for the 2005 DTM season due to production car model change. The Audi A4 DTM, based on the 2005 production car model, distinguishes itself at first glance from last year’s championship winning car through its prominent single-frame radiator grille and the new bodywork shape. However a great deal was also done underneath the skin during the winter. “We have tried to include all the knowledge gleaned during our first DTM season in order to build the best possible car,” explains Audi Motorsport Head Dr Wolfgang Ullrich.
“We were newcomers in the DTM last year,” confirms Wolfgang Appel, Head of Vehicle Technology at Audi Sport. “The 2004 car was relatively conventional. In contrast, the new Audi A4 DTM has many innovative detail solutions, which have previously not been seen on a touring car.” His colleague Ulrich Baretzky, Head of Engine Technology at Audi Sport, speaks of “extensive modifications in all areas”.
The development of the new Audi A4 DTM began immediately after the close of the 2004 DTM season, the roll-out was held on schedule on 14th February 2005 in southern Spain. “2004 was our first season in the DTM,” explains Project Leader Stefan Aicher. “That’s why it was so important to be able to start testing as soon as possible last season. This time we started as late as possible to enable us to incorporate all the data up to, and including, the last race in 2004 into the new project. Our target was to develop the best possible car on which only detail work could be carried out before the start of the season.”
The Audi Sport technicians spent many hours in the wind tunnel. The new single-frame radiator grille necessitated the design of new air ducting and channelling in the area of the front bumper. The cooling air for the engine, brakes and cockpit is now channelled through the single-frame. For example, there are no additional air intakes in the A4 DTM car’s front bumper. At the same time the entire aerodynamic configuration of the A4 DTM was optimised. The loss of rear wing efficiency, because of a common Gurney stipulated by the regulations, has, to a large extent, been compensated for by the Audi engineers’ intensive wind tunnel work.
Weight reduction and improving the centre of gravity height and weight distribution was the main focus of attention on the chassis side. The 2005 A4 DTM can be set-up more easily to suit the various circuits and is even more user friendly than its ground breaking predecessor in this point. The mechanics now only remove the boot during set-up work. During a pit stop, the air jacks are no longer activated from the rear but from the rear left door. Other modifications were also aimed at reducing the time spent during the relatively short five-second pit stops.
The Audi drivers are happy about the improved level of comfort, particularly the reduction in cockpit temperature due to the optimised cooling air ducts and improved insulation of the heat sources. Furthermore, defending champion Mattias Ekström & Co now sit even more in the centre than before in ventilated seats.
While last year’s cars retain the X-trac gearbox, Audi chose the slightly lighter gearbox for the new A4 DTM.
Numerous details of the Audi A4 DTM car’s V8 engine, producing almost 460 hp, were reworked, which led to a noticeable increase in power, especially in the lower and mid rev range. The Audi A4 DTM 2005 is proof that a championship winning car can be improved. However, it must compete with 15 kilograms more ballast than its predecessor – this is what the DTM regulations want to stiplutate.