Boasting BMW's 4.4-litre 8-cylinder within the engine bay of the top-of-the-range 645Ci Convertible, the new model has all the power and refinement of a truly outstanding driving machine. Indeed, this engine recently received the International Engine of the Year 2002 Award that rewards BMW for developing and building the best 8-cylinder in its class.

The top performance of a thoroughbred sports car

This praise by experts is confirmed by convincing facts and figures: Maximum output of 245 kW/333 bhp at 6100 rpm, maximum torque of 450 Nm/332 lb-ft at a moderate 3700 rpm.

Clearly, this kind of power means dynamic performance on the road, the 645Ci Convertible accelerating dynamically to a top speed limited electronically to 250 km/h or 155 mph. Acceleration from 0-100 km/h takes just 6.1 seconds in the manual gearbox model (versus 6.2 seconds with automatic transmission), and in fourth gear the manual gearbox version covers the sprint from 80 -120 km/h (50 - 75 mph) in 5.5 seconds - clear proof of the engine's irresistible muscle and clear confirmation of that extra power and safety so important when overtaking another vehicle. Perhaps the most important point, however, is that the V8 offers an almost sensual driving experience, making it an outstanding pleasure to savor the pure agility and dynamism developed so spontaneously even when pressing down the gas pedal ever so gently.

Leadership in engine technology for efficient dynamics

This supreme performance and the equally outstanding refinement of the engine are attributable first and foremost to infinite control and adjustment of virtually all engine parameters such as valve timing (bi-VANOS), valve lift (VALVETRONIC), and the length of the intake manifold.

A further feature is the currently most advanced and sophisticated engine management masterminding not only the engine functions as such, but also the Dynamic Drive Control (DDC) for even more sporting and dynamic drive characteristics at the touch of a button. Monitoring the car's on-board power management, DDC switches off power-consuming items currently not required in order to provide sufficient energy to other units and power consumers taking priority at any given point in time.

Finally, DDC also controls the innovative air flow and supply system behind the BMW kidney grille ensuring exactly the right flow of air for cooling the engine and ancillary systems by opening the air vents as required.

Otherwise, when not needed, the air vents remain closed in the interest of superior aerodynamics and to warm up the engine more quickly to its normal operating temperature.

The V8 power unit is a genuine trendsetter also in terms of emission control: Complying with the currently strictest EU4 emission standard in Europe, the BMW 645Ci Convertible already fulfills the requirements today not coming into force within the European Union until 2005 - which in Germany and Sweden qualifies the lucky owner of this car for a reduced rate of road tax. In the USA, in turn, the 645Ci Convertible is rated as an LEV (Low Emission Vehicle), again with all the usual advantages.

This superiority is ensured by the two-chamber exhaust system featuring catalytic converters close to the engine itself, completely welded and made of stainless steel in the interest of a long service life. Exemplary fuel economy and environmental compatibility thus prove that the BMW V8 is exactly the right engine for the driver's emotions and common sense all in one.

A deep, throaty rumble as a clear sign of 8-cylinder supremacy

The exhaust system with its two striking, flat-oval tailpipes appeals to the passion and common sense of the enthusiast also in its second function by giving the new 6 Series that unique sound of a sophisticated V8: Hardly audible when idling, the engine quickly builds up that "beefy" rumble of an 8-cylinder so typical of a large-capacity sports car power unit when revving up, without appearing pretentious or obtrusive at any time. On the contrary - both the occupants and passers-by will perceive the engine as a deep and throaty chortle - as a perfect reflection of superior power and an appropriate acoustic message highlighting the sporting and dynamic ambitions of the new BMW Convertible.

Six gears for the right ratio at all times

The 645Ci Convertible comes as standard with a six-speed manual gearbox. And despite its low weight of just 53 kg or 117 lb, the gearbox is designed for maximum torque of 600 Nm or 442 lb-ft and a speed limit of 6500 rpm, making it one of the most high-powered manual gearboxes for a passenger car.

Top speed comes in both fifth and sixth gear, in the latter case with an even lower interior noise level thanks to the reduction in engine speed. Gearbox noise, finally, is additionally reduced by the high-rise gear flanks running with a large side angle and with optimum overlap.

With sixth gear serving primarily to ensure smooth and fuel-efficient motoring at high speeds, the gear increments in the lower gears give the 645Ci extremely powerful acceleration at all times and at all speeds, enabling the driver to capitalize on engine power much more efficiently than with a five-speed gearbox.

Offering a crisp, smooth and light gearshift again typical of BMW, the manual gearbox is even more comfortable and precise than before. This is furthermore the first gearbox connecting the gearshift via the central shaft with a gearshift gate within the gearbox housing itself, gear travel transmission featuring swinging arms in order to reduce gearshift forces on the central gearshift shaft.

SMG technology: shifting gears like in Formula 1

Available as an option, the six-speed Sequential Manual Gearbox offers the sporting and ambitious driver a remarkable choice: He/she can shift gears either like in Formula One race cars by means of paddles on the steering wheel or by briefly "flicking" the center gearshift lever in the desired direction.

In each case the gearbox control unit is informed by an electric cable (shift by wire) of the gear selected, the control unit reducing engine power and torque for split-seconds during gear transition, disengaging the clutch, shifting the gear as such, engaging the clutch again, and finally building up engine power. The clutch pedal, therefore, becomes a thing of the past and the driver is not even required to take his foot off the accelerator when changing gears.

As the name indicates, the Sequential Manual Gearbox shifts gears in sequence, avoiding any risk of shifting to the wrong gear in the process. Briefly pushing the shift lever or the paddles several times in a row, the driver is nevertheless able to "skip" a gear whenever he wishes.

A further important advantage of SMG is that the driver is able to leave his hands on the steering wheel when shifting gears, since he only needs his fingers to operate the paddles - and this, clearly, means extra safety, for example on a winding mountain road. The main point, of course, is that the a sequential gearshift is faster than any other manual shift process, SMG shifting gears in just 150 milliseconds and significantly enhancing the dynamic performance and sporting character of the 6 Series in the process.

Whenever the driver does not feel like shifting gears manually, he can leave things to the Gearbox Control System in the Drive Mode: Once pre-selected from the central shift lever, this system shifts gears automatically on the 6 Series as a function of map control and the respective driving situation, the gear currently in mesh being clearly presented to the driver on the instrument panel.

Six-speed automatic transmission combining dynamic performance and motoring comfort

Available as an option, the six-speed automatic transmission also improves the car's acceleration and start-off performance with its first gear designed for supreme power and traction. At high speeds, in turn, sixth gear reduces engine speed, helping to minimize driving noise and fuel consumption in the process. And featuring BMW's electronically masterminded Adaptive Transmission Management (ATM), the automatic transmission adjusts to the specific kind of driver and driving conditions, serving, for example, to avoid unnecessary gearshifts in bends or stop-and-go traffic.

Also integrated in the automatic transmission, Steptronic even allows the driver to shift gears manually: All you do is move the gearshift lever from automatic position "D" to the left into shift lane M/S in order to activate the Sports gearshift programs. Then, by flicking the selector lever forwards or backwards, the driver can change gears within the Steptronic mode any way he wishes.

Making the 6 Series even more dynamic at the touch of a button

Pressing the DDC Dynamic Drive Control button standard on all transmissions, the driver is able to change the characteristics and features of the drivetrain and steering for even more sporting and dynamic performance in the interest of enhanced driving pleasure.

Source: BMW AG

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