While the A4 1.8T, the touring car's closest cousin, features 280mm ventilated front and rear discs, the A4 racecar has 343mm in diameter and 32mm thick vented discs at the front and 330 X 28mm discs at the rear. Audi is able to use this particularly large rear brake setup because the quattro all-wheel-drive system allows the rears to be further maximized than front-wheel-drive cars due the quattro system's ability to keep the rear wheels from locking up. ABS is not used in accordance with FIA Super Touring regulations.
Pads on the system are Performance Friction carbon-metallic and asbestos free, designed to minimize brake fade. Audi Sport developed the pad compound in cooperation with the American owned company based in Munich. Rotors are slotted. Although most teams in the multiple series choose Brembo or AP Racing, the Audi factory team uses brakes manufactured by a British manufacturer named Alcon. The system is fully adjustable from front to rear via a cockpit dial and, unlike the A4 1.8T, is not power assisted. Though rarely altered once set up for a specific venue, adjusting the balance during the race allows the driver to compensate for decreasing fuel levels that change the car's own balance. This setup, significantly larger than stock, allows for the drivers to brake much later and harder when approaching each turn.
Regulations also state that the racecar's suspension layout must be identical to that of the road car, though modifications of the setup are allowed. The A4 Touring Car rides on 8JX19 forged racing spec OZ 16-spoke alloys in dry weather and forged OZ 5-spoke alloys in wet weather to prevent confusion during pit stops. The OZ alloys are held on with center lock hubs and shod with 215/650 R19 tires.
Inside the trunk, the fuel tank is placed in the center of the car where it is also filled. "Fast filler caps" are not permitted under the FIA rules.
In the cockpit, anyone familiar with the opulence of Audi's smallest sedan might have a hard time recognizing what car they were even in, with the small exception of the top dashboard panel. Luxurious appointments such as leather seats and wood-trimmed components are replaced with bare metal, the aforementioned steel roll cage and carbon fiber composite panels.
Impact protection was a big issue for Audi, who even conducted the world's first crash test for racecars at its road car crash testing facility in Ingolstadt. An Audi 80 Competition racecar was launched into the side of an A4 racecar at 50mph in an effort to perfect their new rollbar safety system.
Audi's roll bar is a unique design that implements X-patterned bars across the front door apertures and called "Side Impact Security Concept". The system also uses two layers of absorbent foam with a strong carbon-fiber partition plate attached to the rollcage.
A Sabelt six point safety belts, and a Recaro racing seat further assure the driver's safety.
Plenty of data was recorded during the highly expensive crash test. Audi recorded much of it for the purpose of sharing it with the FIA for future implementation of safety programs. Interestingly, the measurement for head injury on the crash test dummy was below the maximum value allowed for a road car tested at 30mph.
Standard instrumentation is replaced with various electronic readouts that are centralized more effectively to the view of the driver. On the driver's right is the sequential gearshift lever, located next to two slider controls that handle on-the-move adjustment of the front and rear anti-roll-bars. To the right of the slide controls is a dial for brake bias control. The console above the driveshaft houses the rest of the switches, which would normally be found on the dashboard of a production car.