Automotive Intelligence - the web for automotive professionals and car enthusiasts
February 16, 2012
The self-locking crown-gear center differential works together with the torque vectoring system, which acts on all four wheels. If the load on the inside wheel is reduced too much while the car is being driven dynamically, the torque vectoring system brakes it slightly before unintended slip can occur. Audi offers the sport differential, which uses two superposition stages to actively distribute the power between the rear wheels, as an option.
Aluminum in abundance: the chassis The chassis of the Audi RS 4 Avant is a very complex design. Many components of the five-link front suspension and the self-tracking trapezoidal-link rear suspension are made of aluminum. The new speed-dependent power steering is a highly efficient electromechanical system with a direct steering ratio for highly precise road feel. It helps the driver stay on course by making slight steering corrections when braking on surfaces with different amounts of grip.
The taut RS setup lowers the body by 20 millimeters (0.79 in) compared with the Audi A4 Avant. New, polished 19-inch, ten-spoke forged aluminum wheels shod with 265/35-series tires are standard. Audi also offers 20-inch wheels with 265/30-series tires. These are available in a new, polished, titanium-look, five-V-spoke design plus two additional variants in the five-arm rotor design.
Mounted behind the large wheels are internally vented wave disc brakes measuring 365 millimeters (14.37 in) in diameter up front. The steel friction rings with their wave-like outer contour are perforated and connected to the aluminum brake caps via pins. This concept reduces tensions, quickly dissipates heat and prevents transmission of temperature peaks. The new shape of the friction rings shaves a total of roughly three kilograms (6.61 lb) off the unsprung weight.
The calipers are painted high-gloss black; the front calipers have eight pistons each and sport RS logos. The ESP stabilization system has a Sport mode and can be fully deactivated. For the front axle, Audi offers the option of 380 millimeter (14.96 in) carbon fiber ceramic discs and six-piston calipers in anthracite gray. The ceramic brakes are especially lightweight, robust and durable.
The Audi drive select driving dynamics system is among the standard equipment for the RS 4 Avant. With it, the driver can switch between three modes – comfort, auto and dynamic – to determine the characteristics of the steering, the seven-speed S tronic and the throttle valve. Audi drive select can even vary the sound of the exhaust system, double-declutching when downshifting in dynamic mode. If the car is equipped with an Audi navigation system, a largely driver-configurable custom mode is also available.
In addition to the sport differential, another component available for Audi drive select is dynamic steering. It varies its steering ratio by nearly 100 percent depending on the speed driven and automatically countersteers slightly at the cornering limit for even more precise and stable handling.
Another particularly dynamic damping technology available as an option from Audi is the sport suspension plus with dynamic ride control (DRC). Oil lines and a central valve connect diagonally opposed pairs of shock absorbers. During fast cornering, the system boosts the stabilization of the front outside wheel, for example.
The damping characteristic of the sport suspension plus is variable, with a choice of three settings available via Audi drive select.
The Audi RS 4 Avant is 20 millimeters (0.79 in) longer and 24 millimeters (0.94 in) wider than the A4 Avant, but 20 millimeters (0.79 in) lower. A choice of eight colors is available: one solid and one metallic finish, four pearl-effect colors and the two specially pigmented crystal-effect colors, Prism Silver and Panther Black. The extensively clad underbody integrates air vents for the seven-speed S tronic and the front brakes.
Audi offers exclusive high-grade leather packages for all seating options, including a design package with honeycomb quilting for the RS 4 bucket seats. Rounding out the list of optional equipment is a broad range of state-of-the-art driver assistance and communication systems, including the Bluetooth online car phone that connects the RS 4 Avant with the Internet.
Options for the luggage compartment, which offers up to 1,430 liters (50.50 cu ft) of cargo space, include a rail system with load securing set and a power hatch.
Delivery of the Audi RS 4 Avant is scheduled to begin in fall 2012 at a base price of €76,600 in Germany.
(Feb 15, 2012)