The 5.0-liter V10 engine that powered the 2005 BMW M5 was the S85.
More fully designated S85B50, this naturally aspirated 4,999 cc V10 was introduced in the E60-generation M5. It produced 373 kW, or about 507 horsepower, at 7,750 rpm and developed 520 Nm of torque. Its 8,250-rpm redline helped give the M5 a character closer to a racing engine than a conventional executive-car motor.
BMW’s Formula One experience influenced the S85’s high-revving design. It used double-VANOS variable valve timing, ten individual throttle bodies and sophisticated engine electronics. The engine was also fitted to the E63/E64 M6 and was produced from 2005 to 2010.
The S85 is often confused with BMW’s later turbocharged S63 V8, or with the S54 inline-six used in earlier M cars. Unlike many BMW M engines, the S85 was not derived from an ordinary production BMW engine. Its architecture instead became the basis for the S65 V8 used in the E92 M3.