The 645Ci features the Valvetronic 4.4 liter V8 from the 745i and also offered in the new 5-Series. With 325 hp and 330 lb-ft of torque at 3,600 rpm (SAE standard), the new 6-Series Coupé can cover the sprint from 0-62 mph in 5.6 seconds. Top speed is electronically limited to 149 mph. The 645Ci will be offered with a choice of three different six-speed transmissions driving the rear wheels — a six-speed manual; a six-speed STEPTRONIC automatic; and a six-speed Sequential Manual Gearbox (SMG) featuring both a gearshift lever and shift paddles on the steering wheel.
The new 645Ci comes standard with BMW's Driving Dynamic Control (DDC). Operated by a 'Sport' button on the center console, DDC sharpens up throttle reaction for more responsive acceleration, as well as producing a more direct feel from the speed-related, power-assisted steering. When fitted with SMG or the Steptronic automatic, DDC also shifts gears at higher revs and tightens shift speeds in the SMG to 150 ms. The new coupé also offers a range of control systems and options shared with the new 5-Series, including Dynamic Stability Control (DSC) with Dynamic Traction Control (DTC), and optional Active Steering, Active Roll Stabilization, Active Cruise Control and Adaptive Headlights. An optional Head Up Display will be added later. In addition the new 6 Series Coupé utilizes run-flat tires, allowing the driver to continue for a certain distance even when a tire is completely flat.
As in the new 5-Series BMW uses a range of lightweight materials to keep weight to a minimum. The front section of the car is significantly lighter than steel thanks to lightweight aluminum construction. The trunk lid is sheet-moulded composite, the hood and doors are aluminum and the front fenders are thermoplastic. The lightweight all-aluminum suspension of the new 6 Series Coupé keeps unsprung weight to a minimum. All this contributes to a base weight in European trim of around 1600 kg (3528 lb) with weight distribution close to the perfect 50:50 ratio (compare the Jaguar XK8 at 1705 kg and the similarly sized Pontiac GTO at 1690 kg).
The new 6-Series will among the largest of the midsized sport coupés — 4,820 mm (189.8") long, 1,855 mm (73.0") wide, and 1,373 mm (54.1") high — larger than Jaguar's XK8 and similar in size to the Pontiac GTO. As well as ample room for occupants with 2+2 seating, BMW boasts the largest luggage compartment in its class, with enough space for two golf bags and a suitcase. The interior of the new 6-series follows the pattern set by the new 5-Series. An optional glass panorama roof (standard in the US) gives the interior an even more spacious and brighter feel, especially since the panorama roof is much larger than a conventional moonroof. It offers a vent feature and an electric sliding roofliner. The optional Logic7 audio system from Harmon-Kardon gives the car's occupants a level of audio quality previously only offered by high-end home entertainment systems.
Introduction of the new 6-Series to European markets is planned for late 2003 (December 2003 in the UK), in the US from the spring and other overseas markets from the second quarter of 2004.