tIANcI;757563 said:
Best FC will come with your foot. I noticed that on my e90 325. My average is about 13l for town driving. The manufacturers claim on FC does not come from real life testing. Its only good for comparison. They got their own set of tests for it.
Information about the Fuel efficiency TEST
Preliminary values based on the ECE driving cycle; other values not available at present
All engines meet the EU5 emissions standard. Fuel consumption is determined in accordance with the
ECE driving cycle (93/116/EC). Made up of approximately one third urban traffic and two thirds extra-urban driving (based on the distance covered). CO2 emissions are measured in addition to fuel consumption as such. Fuel consumption levels are calculated based on vehicles with standard equipment. Special equipment (e.g. wider tyres) can have a significant impact on fuel consumption levels.
Unladen weight (EU) in kg: The value given includes the tank filled to 90 % capacity together with 68 kg for the driver and 7 kg for luggage. Unladen weight applies to vehicles with standard equipment. Optional equipment may increase this figure.
Rated output: BMW recommends the use of super unleaded 95 RON fuel. Unleaded RON 91 fuel or higher with a maximum ethanol limit of 10% (E10) is also permitted.
The performance and fuel consumption rates listed are based on the use of RON 98 fuel
ECE test cycle
Test procedure
The cycle must be performed on a cold vehicle at 20-30°C (typically run at 25°C). The cycles may be performed on a flat road, in the absence of wind. However, to improve repeatability, they are generally performed on a roller test bench. This type of bench is equipped with an electrical machine to emulate resistance due to aerodynamic drag and vehicle mass (inertia). For each vehicle configuration, a look-up table is applied: each speed corresponds to a certain value of resistance (reverse torque applied to the drive wheels). This arrangement enables the use of a single physical vehicle to test all vehicle body styles (Sedan, hatchback, MPV...) by simply changing the look-up table. A fan is coupled to the roller bench to provide the vehicle air intakes with an airflow matching the current speed. Many more tests can be performed during vehicle development with this arrangement than with conventional road tests.
The test is conducted with all ancillary loads turned off (Air conditioning compressor and fan, lights, heated rear window, etc.)
Measurements
Several measurements are usually performed along the cycle. The figures made available to the general public are:
Urban fuel economy (first 780 seconds)
Extra-Urban fuel economy (780 to 1180s)
Overall fuel economy (complete cycle)
CO2 emission (complete cycle)