German Car Zone

BMW SA driving down emissions

29/05/2008 10:54

Lance Branquinho


With oil prices seemingly beyond the $100 tipping point forever and climate warming an everyday t-shirt-wearing reality, BMW has engaged emission challenges in a unique way.
Although claimed as a leader in Hydrogen technology - despite an inexplicable lack of Hydrogen refuelling infrastructure worldwide hampering any sensible roll out of this technology - BMW is helping its customers drive to greater efficiency and lower emissions by doing what they do best: engineering.
The new design and engineering philosophy is called Efficient Dynamics and aims at making BMW cars as light and efficient as possible.
Lean and clean
Using lightweight materials, whilst still retaining design integrity and strength, combined with tyres offering less rolling resistance produces efficiency gains.
Tyre sidewall flex, for example, causes energy loss and employing tyres with more rigid sidewalls redresses the issue.
The latest range of BMW direct-injection engines ensures optimal levels of combustion efficiency by running very high, efficient direct injection pressures. Another engine related technology is "auto stop start", which switches off the engine when stuck in traffic as the driver engages neutral and only fires up again as one depresses the clutch to engage first gear before moving off.
Powering on demand
A key design principle of the efficient dynamics programme has been eliminating unnecessary powering of ancillaries when their functionality is superfluous. For example, on a cold morning it's hardly practical to have engine cooling functions running. Similarly power steering pumps hardly have to be active continuously when running on a straight section of highway at speed.
Essentially with efficient dynamics, ancillaries only run "on demand", eliminating huge energy waste tolerances by only powering various belt and pump driven systems when they are required.
Kinetics management
Harnessing kinetic energy and redistributing it is achieved via brake regeneration. Although not perpetual motion technology, brake regeneration utilises captured kinetic energy and feeds it to the battery as soon as a driver brakes or takes a foot off the accelerator.
Ultimately this reduces the amount of power the battery takes from the engine and hence lowers fuel consumption. When the driver presses the accelerator, on the other hand, the alternator is decoupled from the drivetrain.
Aerodynamics exert a huge influence on vehicle dynamics, as the preeminent positions aerodynamicists occupy in Formula 1 illustrates. With regards to a road car, constant airflow through the radiator increases air resistance and affects aerodynamics negatively, increasing vehicle resistance and requiring more power to keep a constant speed. Fitting electrically controlled vents in front of the radiator to open and close the cooling air inlets allows airflow only when required, and in turn reduces air resistance and fuel consumption.
Local conditions
South Africa's sub-standard fuel qualify unfortunately precludes the local market from receiving many of the BMW efficient dynamics features.
The M3 does feature brake regeneration locally, and low resistance tyres are available too. Unfortunately 100% sulphur-free fuel is a prerequisite for the latest, high-pressure, direct injection engines and with the department of minerals and energy unable to fix a timescale for sulphur eradication, consumers are denied the full spectrum of fuel saving technologies.
Climate factors hamper the full efficient dynamics deployment locally, too. The aerodynamics package, for example, would simply not function within the perpetually warm South African environment, where an engine necessitates constant cooling airflow.
Although many enthusiasts fear environmentally-friendly fuel consumption and emission reducing technologies as the beginning of the end of driving dynamics, BMW has proved how driving pleasure can seamlessly integrate with substantial efficiency gains.
Consumption across the range of cars fitted with driving dynamics - primarily 1, 3, and 5 Series models - has dropped by an average of as much as 23%. It has also allowed BMW to now sport 21 models producing less than 140g/km of CO2.