Inside, the 2006 Audi RS 4 blends luxury and sport in equal parts. Serious sports seats with inflatable bolsters conform exactly to the driver’s body. And, just like in motorsports, the steering column tapers, aluminum foot pedals are included, and a starter button in the center console fires the RS 4. A special button on the steering wheel modifies the software controlling the accelerator, allowing the driver to reprogram the RS 4 for sharper engine response. Leather, aluminum, and carbon fiber decorate the cabin.