There are lots of things wrong with the NEDC, the process via which cars sold in Europe have their emissions and fuel consumption calculated.
The chief grumbles are that the New European Driving Cycle isn’t new, bears no resemblance to European conditions and features no driving. Other than that, it’s spot on.
The NEDC, last revised in 1997, is usually conducted in a laboratory on a rolling road, where it’s most repeatable. Manufacturers can switch off ancillaries and set the ambient temperature, and the whole shebang lasts only 11 (stationary) kilometres – some urban driving and some higher-speed driving, after which you get a combined total.
A manufacturer can conduct the test itself, as many times as it likes before the car goes on sale, until it has a result it’s happy to publish; and although an engineer has to use the pedals to match speeds and acceleration points, it is, according to my colleague Mark Tisshaw, “like playing a really hard game of Space Invaders with your feet”, rather than driving.
The number that comes out of the end is the one that manufacturers quote, and that we quote in our first drives until we’ve had the chance to obtain a more realistic number ourselves.