The 6-series returns. The 645Ci will be powered by the 4.4-liter V8 from the 7-series. This engine produces 325 hp and 330 lb-ft of torque. A choice of six-speed transmission include a SMG option. US sales will start in spring of 2004.

The 6-series returns to the lineup in 2004. Based on the new 5-series, the only model initially offered is the 325hp 645i.