At the same Innovation Day 2012: Efficient Dynamics event at which it introduced its new EfficientDynamics engine family (earlier post), BMW also discussed its approach to Predictive Power Management as an element in its toolkit for fuel savings.
With the aid of navigation-based information, the transmission control and the Foresight Assistant are able to chart the course of the road and the profile of the route, with its hills and descents, as well as the speed limits, and to take these into account for gear selection and vehicle deceleration. Even the turning radius is known to the system before the driver reaches the bend in the road.
The Predictive Power Management system sets the vehicle up for the approaching road situation, depending upon which of the modes is activated on the Driving Experience Control (SPORT, COMFORT or ECO PRO); the vehicle responds with the desired driving characteristics.
If the driver selects the SPORT mode on the Driving Experience Control, the Predictive Power Management system uses the information supplied by the navigation system to implement a dynamic, vigorous gearshift strategy. When the vehicle approaches a bend on a country road, the automatic transmission shifts down to the most appropriate gear on its own initiative and also uses the braking action of the engine if necessary. All of the shift operations will have been completed, just as the vehicle goes into the bend.
The next bend in the road is detected and recognized as a following bend. The system identifies the radius of the bend and the transmission remains in the optimum gear. In this way, a higher level of drag torque can be readied when approaching bends. A greater amount of traction power is held in reserve, available for acceleration and unnecessary gearshifts and gear hunting in or between bends is avoided. This precisely-conceived strategy relieves the driver and enhances both ride dynamics and driving pleasure. The Predictive Power Management system works in a similar manner at roundabouts, crossroads and junctions. The Predictive Power Management system also reacts to turn signals, regardless of the course of the road ahead.
In ECO PRO mode, a number of features are active which make savings of up to 25% possible, depending on the individual driving style. For example, the navigation system selects an ECO PRO route and informs the driver of the anticipated fuel savings. Upon request, the Foresight Assistant provides driving tips to increase efficiency even further. Additional features to increase efficiency are coasting, in which the engine and the drivetrain are decoupled and the vehicle rolls freely along, and the recording and evaluation of routes by the ECO PRO Analyzer.
One of the advanced features of ECO PRO mode is the Foresight Assistant, which in conjunction with the Professional navigation system, provides timely information on the road ahead at an early stage and can give the driver tips on fuel-efficient driving, if so desired. These can be circumstances ahead that require a reduction in speed. The Foresight Assistant takes into account speed limits, bends in the road, built up areas, roundabouts, turns off of the route and motorway exits. An indicator on the instrument panel and/or the information display allows the driver to respond to these appropriately. The Foresight Assistant allows the driver to make the best use of coasting.
The new coasting mode enables the engine to be decoupled when operating in overrun, at speeds of between 50 and 160 km/h (31 to 99 mph). As soon as the driver takes his or her foot off the accelerator pedal, the vehicle coasts, unaffected by the engine drag torque and with significantly less deceleration; the engine idles, fuel consumption is at a minimum. In this way, the kinetic energy of the vehicle is exploited and fuel savings of up to 5% can be realized by driving predictively. The coasting feature is indicated both on the instrument panel and on the information display but can be deactivated if so desired. A touch on the brake pedal restores the connection between the engine and the automatic transmission and the vehicle decelerates in overrun. Excess braking energy, if any, is recovered and stored in the battery.
In addition to calculating the fastest and shortest routes, the BMW Professional navigation system can also show the driver the most economical way to get to the destination. To take advantage of the savings potential the ECO PRO Route provides, ECO PRO mode needs to be selected. The system then presents an appropriate route, taking into account the current traffic situation and the profile of that particular stretch of road. The aim of this calculation is to reduce fuel consumption, while keeping the extra time required to an absolute minimum.
This new system gives the driver the opportunity to weigh the extra time required against fuel savings and to make his own decision. The savings that can be achieved on each route are displayed as a percentage. In the event of traffic congestion, the system will suggest alternative routes. The individual driving style of each driver is the final factor which is taken into account when making the calculation. In order to achieve this, the system analyses the consumption behavior of the vehicle in a variety of different driving situations.
The ECO PRO Analyser provides drivers with the opportunity to analyze their own driving styles, using the free BMW Connected App. With this app, a driver can transfer the data collected during the last few journeys quickly and easily to his or her iPhone. A star-based rating scale evaluates the efficiency of driving driving.
Intelligent power management, which includes coasting, the Foresight Assistant and ECO PRO Route can reduce fuel consumption by a further 5%.