You have picked up your shiny new car from the garage and are gingerly driving it around town with pride to get the feel. You probably average more than 10,000 miles per year what with trips for work and outings at the weekends so you have picked a mid-sized diesel engine with a turbo for those long motorway journeys.
But will the fuel economy of your car match that of the one in the advert that caught your eye? There has been some hubbub over the last couple of years about car manufacturers advertising incorrect or possibly unrealistic fuel consumption figures. So why is there such a discrepancy?
The answer is, of course, to do with how the real world differs from the test conditions. To comply with the New European Driving Cycle (NEDC) the vehicle economy tests are carried out in strict laboratory conditions. You may think that that is great; however, the cars are put on a rolling road in a temperature controlled room with no fluctuations in “weather” such as a real driver would face. Neither is there any hills or corners plus all electrical items like lights, heater, air conditioning etc are turned off.
All these factors will decrease the fuel economy of any car in the real world. However, the biggest difference is that the test is carried out over a total of only 6.8 miles which is so unrepresentative of how people drive it is no wonder the figures seem artificially high.