The B7 platform S4 is the most fresh version of the motor vehicle, having debuted in late 2005. Although Audi classifies it as a original car, the differences between it and the outgoing B6 S4 are primarily ornamental.

Audi has, however, made a few distinguished changes, including adding innovative springs and dampers to the suspension and re-calibrating the quattro scheme to maintain a 40:60 front-to-rear torque split under ordinary conditions. The system is continuously adjustable though, and the torque split can change depending on driving conditions. The new “fish mouth” grill, narrow headlamps, “L” tail-lamps and quad exhaust tips help distinquish the B7 from the previous B6 model.

Fascinatingly enough, German tuner Abt Sportsline decided to give up the V8 and use a modified version of the 2.7t engine in a special high-performance B7 S4 it created, named Abt AS4-R. This car now has a 480 PS (353 kW/473 hp) engine, and can attain a maximum speed of 300 km/h (186 mph), surpassing 100 km/h in 4.6 seconds. Changes to chassis include a stiffer adjustable suspension, with new stabilizers, 19 inch wheels and Dunlop SP Sportmaxx tyres.
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