The engineers at Audi Sport developed the Audi RS 5 DTM according to the DTM’s Technical Regulations that have been in effect since 2012. They particularly emphasize three aspects: maximum safety, maximum equality of opportunity and maximum cost efficiency.
Since 2012, the organizers of the internationally popular touring car series have been relying on a concept that was initially unique in the world and has since been largely adopted by the Japanese Super-GT Championship as well. Numerous components such as the carbon fiber monocoque, safety elements, the six-speed transmission, the clutch or the carbon brakes are identical on all DTM race cars.
The organizers differentiate between specification, standard and listed components. Specification components are purchased by the automobile manufacturers from the DTM’s central suppliers. Standard components may be produced by the manufacturers themselves based on specified requirements. In addition, there is a list of optional components. As a result, there is still enough room for the automobile manufacturers’ own developments, particularly in the areas of aerodynamics and the suspension. “An RS 5 DTM consists of some 4,000 parts,” says Dieter Gass, Head of DTM at Audi Sport. “Less than 100 of them are specification, standard or listed components.”
The pioneering Technical Regulations have reduced the costs of a DTM race car by about 40 percent – while simultaneously increasing the safety and performance of the cars.
Consequently, in terms of technology, the Audi RS 5 DTM with which Audi Sport is chasing the title in 2016 corresponds to the model the brand won the manufacturers’ title with in 2014. To relieve the manufacturers’ budgets, the DTM organizers imposed a freeze on this state of technology by homologation after the third race in 2014 until the end of 2016. In parallel to the production version, the next model change will be coming up for Audi Sport in the 2017 season when the new RS 5 will be launched.
Still, the engineers at Audi Sport continued to optimize minor details on the car again over the past two years within the scope of the regulations. For the 2015 season, for instance, a new, even more efficient basic set-up was developed. Last year, the set-up made a crucial contribution to the ten victories in 18 races. For 2016, Audi Sport has changed the type of wrap, which reduces the weight of the body by a little more than a kilogram.
The all-carbon fiber body of the Audi RS 5 DTM at first glance reveals the close kinship to the production RS 5. The chassis underneath it features a hybrid design weighing a little less than 160 kilograms. The combination of the carbon fiber monocoque and steel cage is extremely strong and, with front, rear and side crash elements, sets standards for a touring car in terms of safety.
With respect to the cell, the DTM has been pursuing new approaches since 2012. The monocoque now weighs only 126 kilograms and the roll cage 32.5 kilograms. At the same time, the safety standards significantly increased when the current regulations were introduced. In longitudinal crashes and particularly in side impacts, the construction proves extremely strong. The entire side panel has to resist a force of 360 kN in a side impact crash test, which equates to about 36 tons.
The RS 5 DTM is 5.01 meters long, 1.95 meters wide and 1.15 meters high. The wheelbase of all DTM cars is 2,750 millimeters. As in the production model, the V8 engine that delivers about 340 kW (460 hp) sits at the front.
DTM race cars have rear-wheel drive, quattro drive is not permitted. The semi-automatic six-speed transmission of the RS 5 DTM is pneumatically operated via paddle shifters on the steering wheel. The shifting events, which are more precise, compared with conventional manual gearshifts, make it possible for the transmission to achieve a mileage of up to 24,000 kilometers. The engine electronics (Bosch MS 5.1), which do not use fuses, and a central display that provides the driver with all the relevant information – such as key tire parameters – feature state-of-the-art technology as well. Data transmission by radio to the pits (telemetry) is not permitted in the DTM.
A large safety fuel tank with a capacity of 120 liters is integrated into the safety cell of the Audi RS 5 DTM. It allows the drivers to complete the full race distance without refueling stops even in the longer DTM races on Sunday.
As specification components on the chassis, the engine sub-frame at the front and the transmission at the rear impose limits on the engineers. The suspension has to be mounted on these elements. Furthermore, steel wishbones and the tube dimensions are specified. Numerous dimensions are defined by the regulations – for instance the wheels. The tires for all DTM race cars are exclusively supplied by Hankook.
With respect to aerodynamics, the possibilities of the engineers are limited as well. The driver, if necessary, can flatten the rear wing angle only by 18 degrees using the drag reduction system (DRS). However, underneath the imaginary horizontal line between the wheel hubs, the engineers have extensive freedom – albeit only with each new homologation. In between, modifications of the specification components are not permitted.
The regulations permit and promote a close reference of the race cars to the production cars, for instance, in the form of the single-frame honeycomb grill which, on the racing version of RS 5, contains the airflow ducts to the engine and the brakes. “On the whole, the regulations in the DTM are very strict,” says Dieter Gass. “Therefore, our engineers are challenged to fine-tune details – within narrow limits.”