BMW announced the production version of the all-new BMW ActiveHybrid 7, which will also premiere at the Frankfurt Auto Show (IAA) in September. The BMW ActiveHybrid 7 will reach America shores in Spring, 2010.
This symbiosis of an upgraded twin-turbo, High Precision Direct Injection, V8 engine with a 3-phase synchronous elec¬tric motor gives the BMW ActiveHybrid 7 a combined output of 455 hp and maximum torque of 516 lb-ft (preliminary figures). Power is transmitted via an 8-speed automatic transmission with the electric motor positioned between the engine and the torque converter. The electric motor receives its supply of energy from a lithium-ion battery developed specifically for use in this automobile.
The BMW ActiveHybrid 7 accelerates to 60 mph in 4.8 seconds (preliminary), while delivering fuel economy approximately 15% better than the 750i. Official EPA ratings will be available closer to the US market launch.
BMW ActiveHybrid technology also provides new features that promote efficiency while preserving comfort. As an example, the BMW ActiveHybrid 7 is the first BMW with automatic transmission to feature Auto Start Stop to maximize efficiency by avoiding engine idling when stopped. Another advantage is that the air conditioning and ventilation system remains fully operational when using Auto Start Stop. In this case, power is supplied directly through the 120-volt on-board network powered by the lithium-ion battery.
Special displays in the instrument cluster and the Central Display inform the passengers of the degree of efficiency and the current operating status of the hybrid components. The ActiveHybrid 7 is distinguished from the 750i by aerodynamically-tuned ten-spoke 19-inch light-alloy Aero wheels, and model designations on the trunk lid, C-pillars, and on the door cutouts. The BMW ActiveHybrid 7 is also available in Bluewater Metallic exterior paintwork.
Like existing BMW 7 Series models, BMW’s first luxury sedan with ActiveHybrid technology will enter the market in two body variants. The extended version of BMW ActiveHybrid 7 has a wheelbase increased by 5.5″, all of which is devoted to the enhanced comfort of rear-seat passengers. Both models are available with a wide range of options from the portfolio of equipment and accessories offered on the BMW 7 Series, enabling the tailoring of the ActiveHybrid 7 to individual tastes and requirements.
BMW ActiveHybrid technology uses energy that would be normally converted into heat through the brakes, and therefore wasted in conventional cars. The BMW ActiveHybrid 7 features an enhanced version of Brake Energy Regeneration already used in some current BMW models running on a combustion engine alone. In this case the integrated electric motor acts as a generator when coasting or applying the brakes, in order to feed electric power into the battery. Brake Energy Regeneration converts some of the vehicle’s kinetic energy into electric power for the on-board network whenever the driver lifts off the accelerator or applies the brakes. On acceleration, electricity is fed back into the on-board network from the lithium-ion battery. This sequence relieves the combustion engine from the task of converting some of its fuel energy into electric current, and thus enables the engine to provide more power directly to the rear wheels. The result is better acceleration even than the 750i, despite the fact that the additional power is obtained in a way that does not require additional consumption of fuel.
When the driver requires only a small amount of brake force, the system uses only the drag of the electric generator (motor). The mechanical brakes are activated only when the driver presses down the brake pedal harder for more stopping power. Dynamic Stability Control controls the balance of electrical and mechanical braking so adeptly that the driver does not even perceive the transition from braking with electric power to braking with the mechanical brake system.
The BMW ActiveHybrid 7 features both a conventional 12-volt on-board network fed by an absorbent glass mat (AGM) battery and an additional battery featuring lithium-ion technology operating at 120-volts. The lithium-ion battery supplies power to the electric motor as required and serves to start the engine. Electric power generated by Brake Energy Regeneration is fed into both on-board networks. The air conditioner compressor on BMW ActiveHybrid 7 is integrated in the 120-volt network. All other electrically operated functions of the car are supplied by the 12-volt network. The two on-board networks are connected by a voltage converter featuring flexible energy management. Both batteries are charged and maintained through Brake Energy Regeneration. The 12-volt battery is fed with energy from the high-voltage network.
BMW found that lithium-ion battery technology offers sufficient energy storage capability while taking up minimal space. The result is that the BMW ActiveHybrid 7 gives up almost no luggage capacity to its conventional siblings (750i and 750Li), because the 120-volt battery is small enough to be mounted underneath the trunk floor. Furthermore, the weight penalty incurred by this battery is minimal, meaning less energy is consumed to carry it. Using this technology enables the ActiveHybrid 7 to maximize storage capacity and acceleration in the hybrid luxury sedan segment. It is the fastest-accelerating hybrid sedan in the world.
The useful energy provided by this high-performance battery is 400 watt-hours. The battery itself is comprised of 35 cells and an integrated control unit which continuously analyzes the charge level and ensures appropriate dependability under all conditions. Despite its high level of performance, the lithium-ion battery measures just 14.6 x 8.7 x 9.1 inches (37 x 22 x 23 centimeters) and weighs a mere 59.5 lb or 27 kg.
Compared with the engine featured in the BMW 750i/Li, this version has been modified in numerous respects to the specific requirements of the BMW ActiveHybrid 7. There is no starter, alternator, or belt drive for the air-conditioning compressor and hydraulic pump. The cooling system has been modified for hybrid operation.
The direct response to the accelerator pedal is impressive when compared either with conventional 7 Series models or existing hybrid vehicles already in the market. Acceleration to 60 mph in 4.8 seconds (preliminary) ranks it among the fastest and most thoroughbred sports cars in the world. Top speed of BMW ActiveHybrid 7 is electronically limited to 150 mph.