In 1989 the 6 Series was supplanted by the 8 Series, but in late 2003 the 6 Series was reintroduced (as a 2004 model), with Coupe and Convertible versions based on the BMW E63 and BMW E64 platforms, respectively. These two models are each available with either a 3.0 L (2996 cc) straight-6 making 190 kW (258 hp DIN) at 6600 rpm and 300 Nm (221.3 ft.lbf) of torque from 2500–4000 rpm (in the 630i) or a 4.4 L (4398 cc) V8 making 245 kW (333 hp DIN) and 450 Nm (331.9 ft.lbf) of torque at 3600 rpm (in the 645Ci). [1] In some markets, the convertible versions are sold as the 630i Cabriolet and the 645Ci Cabriolet.

The V8 in the 645Ci is the N62 motor, the same powerplant used in the 545i and 745i.

Unlike that of the new 5 Series and 7 Series cars, the styling of the new 6 Series has generally received a warm welcome from the BMW community—except, largely, owners and enthusiasts of the E24.

The new BMW M6 made its debut at the 2005 Geneva Motor Show. It is based on the BMW E63/E64 6-Series, introduced in 2005. It shares the same 5.0 L V10 S85 engine and SMG III gearbox with the E60 M5, and produces 507 ps (373 kW) / 384 ft·lbf (521 N·m).

BMW claims it will accelerate from 0 to 100 km/h (62 mph) in 4.6 seconds and has an electronically limited top speed of 250 km/h (155 mph).

The M6 will have the same 'power button' as the M5 which modifies the throttle response. From ignition, the car delivers 400 hp (298 kW), but engaging the button allows the full 507 ps. It weighs 1710 kg (3770 lb) thanks to a carbon fibre roof panel as well as thermoplastic front wings, aluminium doors and bonnet and compound boot lid.

Initially it will only be available as a coupe, although a cabriolet and a lightweight CSL version are expected in 2006 and 2007 respectively. It can be visually distinguished by its deeper front valance with air intakes, more contoured side sills and a rear valance with diffuser as well as four tail pipes.