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Print articleBy autumn 2007, around 40% of all BMW Group (BMW, Mini, Rolls-Royce) cars sold in Europe will come with maximum C02 emissions of 140g per kilometre. From 2008, the number of BMW Group vehicles with a maximum CO2 level of 140g per kilometre increases to 22. Three of them will be Mini models and two of them belong to an additional BMW model line. This extension of the range of especially low-emission models is made possible by the newly developed 4-cylinder petrol and diesel engines for the BMW 3 Series and the market launch of the new BMW 123d and the new BMW 520d.
BMW continues to pursue its Efficient Dynamics strategy with new models optimised for reduced fuel consumption and exhaust emissions. Lower emissions will be a result of more efficient engines and smarter technology that looks after how energy is used and how energy can be reused.
In addition to the in-line 6-cylinder engines, BMW's 4-cylinder engines will also have petrol direction injection. The technology is known as High Precision Injection and enables so-called lean combustion operation across a broad engine speed range, resulting in significant reductions in fuel consumption in everyday traffic. The highly precise and efficient fuel injection is carried out by piezo injectors which are positioned between the valves in the cylinder head and thus in immediate proximity to the spark plug.
From 2008, 4-cylinder engines with High Precision Injection in lean combustion operation will be used in the new BMW 520i, in all versions of the BMW 3 Series and the BMW 1 Series. In addition to the two engines already introduced with a capacity of 2.0 litres each, a new 1.6 litre petrol direct injection engine in the new BMW 116i now also sees its premiere. Even though the three new 4-cylinder engines have an increased power output between 5 and 15kW, fuel consumption will drop by up to 23%.
In future, all models of the BMW 6 Series, BMW 5 Series, BMW 3 and BMW 1 Series as well as the BMW X5 will be fitted with brake energy regeneration. It is the result of intelligent energy flow management which leads to a more efficient use of the energy contained in the fuel and increased dynamic performance on acceleration manoeuvres. By means of brake energy regeneration, the generation of electrical current for the vehicle power supply is focused on the vehicle's trailing throttle and braking phases. During the pulling phases, however, the generator is decoupled, providing more drive energy for conversion into driving dynamics.
The Auto Start-Stop Function was presented for the first time in spring 2007 in the new BMW 1 Series and in the BMW 320i Coup?/Convertible. The function reduces the amount of idling when stopped at junctions or in traffic jams. As soon as the driver puts the gear lever into neutral and removes their foot from the clutch, the engine is automatically switched off. As soon as the driver wants to pull away, they just need to put their foot on the clutch and the engine re-starts immediately.
Other energy management features include the needs-oriented control of ancillary units, the use of electrical steering and a Varioserv steering pump and the decoupling of the air conditioning compressor. For example, needs-oriented control of the coolant pump uses significantly less energy than conventional systems which run permanently at full capacity. The servomotor of the electric steering is only activated when steering boost is required or desired by the driver. With the Varioserv steering pump, the cam ring is adjusted in relation to pressure and volumetric flow so as to avoid the loss of drive train power as the engine speed increases. The power dissipation of conventional air conditioning compressors can also be reduced by means of intelligent regulation. In the new BMW models, the compressor is separated from the belt drive by means of a magnetic coupling as soon as the air conditioning system is out of operation.
These measures reduce the amount of electrical energy required, and as a result the generator has to convert significantly less primary energy into electrical current. A special low viscosity transmission oil contributes to the reduction of frictional loss. What is more, optimised heat management for the rear-axle drive ensures that frictional resistance is reduced more quickly after starting. The reduction of aerodynamic resistance also supports the decrease of fuel consumption. With cooling air flaps which open or close depending on the driving situation and which are actively controlled in some models, the aerodynamic properties of a vehicle can be further optimised.
The driver will also receive support in the choice of the most economical driving style from the gear shift indicator. This system uses data provided by the engine control unit to calculate in each situation the most favourable point at which to shift down or up from the point of view of economical fuel consumption. The signal to change gear appears in the instrument panel. Here an arrow symbol and a figure show which gear would be most suitable for economical motoring.
Not all the features will appear in all the cars, but every car will benefit from the BMW Efficient Dynamics programme.
