BMW 7 EfficientDynamics: Increasing power and cutting-edge functions while lowering fuel consumption and emissions
The BMW 7 Series sets the standard to follow in a host of different ways, and it’s as synonymous with silky smooth drive technology and luxurious comfort as it is with dynamic prowess.
As further confirmation of the Sedan’s superiority, a series of new and optimised drive variants are being brought out in 2012 which boast more than just stunning power and dynamism. A raft of measures have been implemented under the umbrella of the BMW EfficientDynamics development strategy to bring about a substantial reduction in the fuel consumption and emissions figures for the BMW 7 Series compared to the outgoing model.
The BMW 750i and BMW 730d both deliver impressive evidence of this, with CO2 output having been cut by 25 and 17 per cent respectively despite their superior power. What’s more, the entry-level diesel model successfully holds on to its status as the cleanest-running engine of its breed in its class. Finally, the second generation of the BMW ActiveHybrid 7 also continues in the same vein by further raising the bar for energy efficiency.
Top-calibre engineering: supremely efficient petrol and diesel units allied to a cutting-edge eight-speed automatic with an excellent efficiency factor.
The petrol engines in the BMW 7 Series line-up are awash with state-of-the-art technologies, packaged together to create a superb piece of engineering. These include BMW TwinPower Turbo technology featuring twin-scroll turbocharging, High Precision Direct Petrol Injection, Double-Vanos variable camshaft timing and VALVETRONIC fully variable valve timing. The reduced-friction core engines, furthermore, come with a lightweight all-aluminium crankcase, which is a boon for both the efficiency and the agility of the BMW 7 Series.
The luxury sedan’s BMW TwinPower Turbo diesel powerplants likewise showcase the very latest in BMW drive technology. With their latest-generation common rail direct injection, turbocharging and all-aluminium design, the cutting-edge diesel units are blessed with high pulling power, refined running and unsurpassed efficiency. The new range-topping diesel models – the BMW 750d xDrive and BMW 730d – go one better by offering advanced BMW BluePerformance technology, which enables them to easily undercut the EU6 emissions limits.
All engines in the BMW 7 Series are partnered by a highly sophisticated eight-speed automatic transmission, which stands out for its excellent efficiency, compact construction and innovative gearset design. Together with the minimised torque converter slip, high internal efficiency, low friction losses and intelligent transmission control, this creates substantial potential for fuel savings.
Auto Start-Stop, Brake Energy Regeneration, ECO PRO mode.
All BMW 7 Series Sedans come equipped with an Auto Start-Stop function, which can cut fuel consumption by up to six per cent. The standard specification also includes Brake Energy Regeneration, meaning that power for the vehicle electrical system is only generated during overrun and braking phases where possible. When the engine is under load, the alternator can often be disengaged. This not only means that electricity can largely be generated with zero impact on fuel consumption, it also endows the luxury sedan with even livelier acceleration.
Finally, the Driving Experience Control switch gives drivers the option of selecting the optimised ECO PRO mode which, by modifying the powertrain management and programming the heating and air conditioning, heated seats and exterior mirror heating to operate for optimum efficiency, fosters an economical driving style and reduces fuel consumption by as much as 20 per cent.
New: coasting mode, proactive driving assistant and advance preparation of hybrid drive system.
The extended ECO PRO functionality includes the new coasting mode, which is designed to decouple the combustion engine when it is overrunning at speeds between 50 and 160 km/h (31 – 100 mph). With this mode activated, the BMW 7 Series Sedan is subject to a far lower rate of deceleration as it freewheels along the road with no engine braking effect and minimal fuel consumption. Through proactive driving, the kinetic energy built up by the vehicle can be harnessed in this way to achieve fuel savings of as much as five per cent. The coasting function is clearly visualised for the driver’s benefit in the multifunctional instrument cluster and the information display, and can also be deactivated if desired.
With the exception of the BMW 760i, all engine variants feature a proactive driving assistant that can be switched on via the ECO PRO mode. Drawing on the latest navigation data, it recommends advance adjustment of the car’s speed with the aim of saving fuel. These tips for more efficient driving are shown in the multifunctional instrument cluster and in the central Control Display.
The BMW ActiveHybrid 7 is also able to switch to coasting mode. In this case, the combustion engine switches off completely when overrunning, allowing the Sedan to glide along with zero local emissions.
The system of intelligent energy management furthermore allows proactive analysis of the driving situation ahead with the aim of priming the hybrid drive components for maximum efficiency. This is achieved by integrating the power electronics with the standard-fitted Professional navigation system. Based on the data gleaned in this way, such as route topography, speed limits or traffic levels, the vehicle can be prepared in advance and the available energy deployed as efficiently as possible. For instance, a longer downhill stretch can be used to recharge the hybrid battery so that the vehicle can be driven on purely electrical power through a residential area on the “home straight”.
On-demand control of ancillary units saves energy.
Intelligent energy management in the BMW 7 Series is further enhanced by the ancillary units, which consume significantly less energy compared with conventional systems. Examples include the on-demand coolant pump, the electronically controlled oil pump and the new Electric Power Steering system, which offers potential savings of up to three per cent. The disengageable air conditioning compressor works on the same principle, minimising power drain by the system.
Intelligent lightweight design brings further reduction in fuel consumption and CO2 emissions.
Intelligent lightweight design is integrated into all areas of BMW vehicle development work and into all components, from the body and engine to the suspension. Besides high and ultra-high-tensile steels and plastics, state-of the-art composite materials are also employed. Finally, increased use of aluminium components in the engine and suspension systems as well as for the bodywork has also further reduced the weight of the relevant assemblies.
Reducing aerodynamic drag also helps to lower fuel consumption. As the excellent drag coefficient figure of cd = 0.28 would suggest, the aerodynamics of the BMW 7 Series have been finely honed in a state-of-the-art wind tunnel.
The optimised aerodynamics also bring benefits for acoustic comfort and roadholding. In particular, the vehicle’s underside plays an instrumental role in minimising lift forces, as the aerodynamically efficient design with streamlined panelling provides a high degree of sealing. Also, the front aprons are designed to create an “air curtain” effect which reduces turbulence around the front wheels – again reducing drag. The aerodynamically designed wheel arches and various air deflectors likewise have a fuel-saving effect.