For the 2nd gen S4, Audi switched to the smaller B5 chassis and employed a new 90-degree 2.7 liter V6 engine with 5 valves per cylinder, twin sequential turbochargers (“Bi-Turbo”) and dual intercoolers. A 6-speed manual or 5-speed tiptronic automatic transmission was available to transmit the 251 bhp and 258 ft-lbs of torque to the 4th version Quattro AWD system. At the time, these performance figures made the S4 one of the quickest sedans in the world. Europe’s RS4 version of the car produced an astounding 375 bhp and 325 ft-lbs of torque. Production for the B5 series began in 1997, although it wasn’t available in the U.S. until 1999. Audi closed out the 2nd gen cars in 2001, although they were still sold in North America through 2002.