Audi is introducing its new sporty top models in the midsize class - the S4 and the S4 Avant. Their engine, a three-liter V6 with direct fuel injection and mechanical turbocharging, delivers a powerful 245 kW (333 hp). It accelerates the S4 to 100 km/h (62.14 mph) in just 5.1 seconds, but on average only uses 9.7 liters of fuel per 100 km (24.25 US mpg). The quattro permanent all-wheel drive system transfers its power to...