Fuel consumption test methodology

[Matra et Alpine]

This comes up often in discussino about "real" fuel consumption versus published figures to varying standards.

So here's the European version ............

FUEL CONSUMPTION TEST (Directive 80/1268/EEC as amended by 2004/3/EC)
The new test has been agreed internationally and provides results that are more representative of actual average on-road fuel consumption than previous tests. There are two parts: an urban and an extra-urban cycle. The test cycle is the same as that used to determine the official exhaust emission classification for the model of vehicle in question.
The cars tested have to be run in and must have been driven for at least 1,800 miles (3,000 kilometres) before testing.
Urban cycle
The urban test cycle is carried out in a laboratory at an ambient temperature of 20°C to 30°C on a rolling road from a cold start, i.e. the engine has not run for several hours. The cycle consists of a series of accelerations, steady speeds, decelerations and idling. Maximum speed is 31 mph (50 km/h), average speed 12 mph (19 km/h) and the distance covered is 2.5 miles (4 km). The cycle is shown as Part One in the diagram below.
Extra-urban cycle
This cycle is conducted immediately following the urban cycle and consists of roughly half steady-speed driving and the remainder accelerations, decelerations, and some idling. Maximum speed is 75 mph (120 km/h), average speed is 39 mph (63 km/h) and the distance covered is 4.3 miles (7 km). The cycle is shown as Part Two in the diagram below.
Combined Fuel Consumption Figure
The combined figure presented is for the urban and the extra-urban cycle together. It is therefore an average of the two parts of the test, weighted by the distances covered in each part.