Drivetrain
Converting Supreme Muscle into Agile Roadholding.
The “Powerdome” on the new BMW 6 Series – that muscular bulge on the engine compartment lid – bears its demanding name quite rightly. For beneath the engine compartment lid you will find the 4.4-litre V8 power unit carried over from the new BMW 7 Series and specially tuned to comply with the sporting character of the Coupé. This engine is indeed a milestone in technology, the winner of the International Engine of the Year 2002 Award rightly referred to as the “Oscar for engine technology”. This prize alone confirms that BMW’s engineers have developed the best power unit in its class.
Maximum output of the V8 is 245 kW/333 bhp at 6,100 rpm, maximum torque 450 Nm/332 lb-ft at 3,600 rpm. The car’s performance on the road reflects this muscle, with top speed limited electronically to 250 km/h or 155 mph, and with acceleration from 0–100 km/ in either 5.6 (manual) or 5.8 seconds (automatic). Acceleration in fourth gear from 80–120 km/h, in turn, is in 5.1 seconds for extra safety when passing another vehicle.
The impression you immediately get on the road is one of sheer pleasure, pressing down the gas pedal only lightly to generate pure agility and dynamism at all times.
Leadership in engine technology: more power, cleaner emissions.
This superior performance is largely attributable to infinite adjustment of virtually all relevant parameters within this eight-cylinder such as valve timing (bi-VANOS), valve lift (VALVETRONIC) and even the length of the intake manifold. Optimum engine management of this kind also ensures superior fuel economy of 11.7 litres/100 km (24.1 mpg Imp) premium fuel (manual) and, respectively, 10.9 litres/100 km (25.9 mpg Imp) (automatic) in the new European combined cycle. And the average change interval for engine oil, finally, is only once every 30,000 kilometres.
The engine is also a genuine champion in emission control: Complying with EU4, currently the strictest emission standard in Europe, the BMW 645Ci already meets the requirements today not to be imposed in the European Union until the year 2005. In Germany and Sweden this means that the car is registered at a reduced rate of tax. And in the USA the 645Ci qualifies as an LEV low emission vehicle.
This efficient emission management is ensured by a twin-chamber exhaust system equipped with catalysts close to the engine, the exhaust pipes themselves being made of long-life, fully welded stainless steel.
Deep, rumbling sound revealing eight-cylinder power.
Through its second function the exhaust system made up of two chambers from front to rear and merging into two striking, oval tailpipes ensures the special V8 sound so characteristic of the 645Ci. Hardly audible when idling, the engine builds up that typical eight-cylinder sound so characteristic of a large-capacity sports car power unit as power increases, without however making a loud or pretentious impression at any time. On the contrary – the occupants will experience the sound of the engine as a deep, pleasant rumble proving convincingly that this is a high-performance power unit and perfectly underlining the sporting and dynamic experience of driving the 645Ci.
The currently most innovative engine control system for perfect drive management.
ME 9.2.1 engine management, the most innovative system currently available, masterminds the outstanding power, torque and emission data of BMW’s V8. And despite its complex functions, this control unit is housed in just one single box within the 645Ci, monitoring and adjusting not only engine functions, but also, inter alia, the car’s DDC Dynamic Drive Control responding to the touch of a button by providing even more sporting drive characteristics.
The ME 9.2.1 control unit also masterminds the active cruise control available as an option, serving furthermore to monitor the on-board power network providing an adequate supply of energy at all times to the various power-consuming items and switching off items not in use. The final function is air flap control for the radiator, again in the interest of optimum efficiency.
Air flap control improving heat and aerodynamic management.
This innovative air flap control unit is housed directly behind the BMW kidney grille and controls the supply of air for cooling the engine and other units by opening the air flaps only when required. Otherwise the air flaps remain closed in the interest of enhanced streamlining, allowing the engine to build up its operating temperature more quickly. The result is a reduction of fuel consumption and exterior noise, with corresponding improvement of the engine’s service life and motoring comfort.
Output and Torque Diagram
Six gears providing the right transmission ratio at all times.
The new BMW 645Ci comes as standard with a six-speed manual gearbox designed and engineered for maximum torque of up to 600 Nm or almost 445 lb-ft. Top speed of 250 km/h or 155 mph limited electronically is achieved in both fifth and sixth gear, the latter allowing a dynamic style of motoring at high speeds and with interior noise reduced to a minimum thanks to the lower speed of the engine. Upright gears with a large inclination angle and their optimum overlap serve additionally to reduce transmission noise. In the lower gears the BMW 645Ci offers outstanding acceleration and pulling force at all times.
The manual gearbox both light, precise and crisp in typical BMW style provides an even more comfortable and smoother gearshift than ever before. For the first time the gearshift is connected via the central gearshift shaft to an internal shift gate. And to reduce shift forces on the central gearshift shaft, gearshift travel is transmitted via swinging arms.
SMG transmission: shifting gears like in Formula 1.
Optional six-speed SMG transmission offers the sporting and ambitious driver remarkable – and enviable – choice: He may shift gears by way of paddles in the steering wheel like in Formula 1 or by simply flicking the central gearshift lever forwards or backwards. In each case this process takes place without a clutch pedal, the SMG transmission operating as an electrical shift-by-wire system to shift gears by itself within fractions of a second. This is done by a hydraulic unit with actuators operating the clutch and actually shifting from one gear to the other. The clutch itself as well as the transmission ratios are the same as on the six-speed manual gearbox.
Whenever the driver shifts gears via the gearshift lever or paddles, the electrical shift-by-wire connection transmits information on the gear chosen to the transmission control unit. This “brain”, in turn, automatically intervenes in the engine to reduce drive forces, open up the clutch, shift gears, close the clutch and build up forces once again.
The basic principle of the Sequential Manual Gearbox is to shift gears in sequence one after the other. But by tipping the gearshift lever or the paddles several times in a row, the driver may skip a gear whenever he wishes. SMG performs the entire gearshift operation in just 150 milliseconds, that is so quickly that the driver will hardly notice what is happening. Indeed, the driver is not even required to take his foot off the gas pedal in the gearshift process.
Through its extremely active configuration, SMG thus enhances the dynamic and sporting qualities of the 6 Series, with sixth gear being conceived for low engine speeds and, as a result, optimum noise control and fuel economy. Again, the car reaches its top speed in both fifth and sixth gear.
Shift and be shifted: SMG in the Drive mode.
The driver who does not wish to shift gears himself can transfer this entire function to the transmission management in the Drive mode. And if he does so via the gearshift lever in the middle, the BMW 645Ci will shift gears automatically according to a specific control curve tailored to the current driving situation. The driver is then informed of the gear currently in mesh by a display in the instrument panel.
SMG for extra safety and dynamic performance.
Opting for the Sequential Manual Gearbox, the driver can leave his hands when shifting gears on the steering wheel, since all he has to do is press the paddles with his fingers – a significant contribution to extra safety, particularly on winding roads. At the same time SMG significantly enhances the dynamic performance and sportiness of BMW’s large coupé, enabling every driver to accelerate just as fast as only a very experienced driver is able to do with a manual gearbox.
Six-speed automatic transmission combining dynamic performance with superior motoring comfort.
Also available as an option, six-speed automatic transmission is first choice for the new BMW, catering both for the sports- and comfort-minded motorist. In its design and engineering, the six-speed automatic transmission is conceived for enormous torque of 600 Newton-metres or almost 445 lb-ft, providing ideal conditions for sports motoring and a comfortable gearshift. The wide range of gear increments offers advantages when setting off also with this automatic transmission, since first gear is laid out for superior traction and pulling force. At high speeds, in turn, sixth gear reduces engine speed in the interest of low noise and fuel consumption. And despite its six gears, the automatic transmission is almost one-fifth lighter than a comparable five-speed transmission unit.
Equipped with electronic Adaptive Transmission Management (ATM), the automatic transmission adjusts perfectly to the type of driver and driving conditions. As an example, it avoids any unnecessary gearshifts in bends or in stop-and-go traffic and, alternatively, shifts automatically to a lower gear when driving downhill in order to use the brake force of the engine. ATM is particularly beneficial in winter, automatically setting off in second gear on slippery surfaces and shifting gears more smoothly and gently to prevent the drive wheels from swerving or skidding out of control.
Do it yourself: automatic transmission also with a manual gearshift.
The Steptronic function integrated in the automatic transmission even allows the driver to shift gears by hand: All you do is move the shift lever from automatic position D to the left into shift lane M/S in order to activate the sporting shift program. Then, flicking the gearshift lever to the front or to the rear, you change gears manually with the help of Steptronic.
Making the 6 Series even more dynamic at the touch of a button.
Regardless of the transmission chosen, the DDC (Dynamic Drive Control) function featured as standard and operated by the touch of a button enhances the sporting, dynamic response of the drivetrain. Steering behaviour also becomes more sporting and dynamic at the same time through the Servotronic function, the engine responding more dynamically by accelerating faster with the same pressure on the gas pedal. Then, pressing down the gas pedal a bit further, the driver obtains an even more progressive, sporting engine response.
On the automatic transmission DDC, depending on the position of the gas pedal, waits longer for higher engine speeds before shifting up to the next gear. In conjunction with SMG transmission, on the other hand, DDC shifts gears even more quickly and dynamically.
A further function of DDC is to change steering forces (not on the Active Steering available as an option), the system thus giving the sporting and ambitious driver even better feedback from the steering.
Apart from the smooth and harmonious set-up of the drivetrain, DDC therefore gives the driver a second, more sporting and dynamic option. And this means enhanced driving pleasure particularly for the sports-oriented motorist enjoying the power and performance of the engine in an even more sporting, spontaneous style.
Gabriel,
2001 CL Type S
2001 Lexus RX300 Silversport