Book MPG compared to actual MPG

According to a recent report by What Car? magazine, the book fuel economy figures released by car manufacturers is ‘routinely too optimistic’.
More than 60 cars were driven on a variety of roads, these ranged from motorways to urban environments. This was opposed to laboratory environment to see this difference.

To verify what has long been suspected by many car owners, What Car? Tested more than 60 cars on a number of different roads. These included motorways and urban environments, as opposed to the laboratory environment commonly used by car manufacturers to simulate real car journeys.

In every single test, the driver of each car tested failed to achieve the same level fuel economy claimed by the different manufacturers.

‘More realistic’

What Car? believes that due to the fact that cars were ‘run heavier’ than in lab tests, its tests provided a far more realistic indication of real-world fuel economy than did manufacturers.

Wide gaps

The cars employed by the magazine for these tests were all fitted with equipment to measure carbon dioxide emissions. The figures from which were used to work out how many miles per gallon each car could actually do.

This state-of-the-art equipment was also used to measure the temperature and humidity of each car’s engine.

Ultimately, tests showed that while some of the cars delivered a fuel economy that was acceptably close to official data, most were significantly different. As a result of the differences between official and actual fuel economy, car drivers will find that they will have to refuel their vehicles more often than they had perhaps anticipated. However, those looking to find a bargain at the likes of can now use the fuel calculator at What Car? to find more accurate information before making their purchase.

While the Jaguar XK Convertible’s official economy of 25.2 mpg was only marginally optimistic against its real-world counterpart of 24.9 mpg. The VW Golf TDI BlueMotion’s official figure of 88.3 mpg compared less favourably to its real-world equivalent of 64.2 mpg.