Fuel consumption is of interest not only to car enthusiasts but also to those more concerned with the economics of running the mode of transport. Often, instead of a single figure for consumption, three figures are given, sometimes with a significant difference in the miles per gallon (mpg).
Official consumption test procedures have been in use since the 1970s. An EU directive means all new cars on sale after January 1st 1998 have been required to be tested. Under the rules the cars tested must have been driven for at least 1,800 miles before testing.
Urban: The urban test cycle is carried out in a laboratory on a rolling road from a cold start. The cycle consists of a series of accelerations, steady speeds, decelerations and idling. Maximum speed is 31 mph, average speed 12 mph and the distance covered is 2.5 miles.
Extra-urban: This cycle is conducted immediately after the urban cycle and consists of roughly half steady-speed driving and the rest accelerations, decelerations, and idling. Maximum speed is 75 mph, average speed is 39 mph. Distance is 4.3 miles.
Combined: This figure is for the urban and the extra-urban cycle together. It's an average of the two parts of the test, weighted by the distances covered in each part.