Figures submitted to consumer champion honestjohn.co.uk reveal a discrepancy between official fuel economy ratings and real performance is costing drivers £4.45billion per year.

Damning research by consumer motoring website HonestJohn.co.uk today reveals that heavily overstated official fuel figures cost UK drivers up to £4.45 billion per year collectively.

The website invited drivers to submit how many miles their cars actually do to the gallon. To date is has collated more than 30,000 entries, covering all major manufacturers and models, with the majority failing to meet official figures. On average cars only achieve 88% of their official MPG figures, forcing drivers to spend around an extra 2p per litre every time they fill their tanks.

According to the research gathered from tens of thousands of HonestJohn.co.uk users, the worst performing car was the Mercedes Benz B-Class (2005-2012 generation), which on average achieves 71.2% of its official fuel economy rating. The Lexus CT200h and Range Rover Evoque come a close second and third in the worst performing stakes, achieving 73.0% and 73.4% respectively. The Vauxhall Astra Sports Tourer (2010-) is also one of the UK’s worst performing cars, according HonestJohn.co.uk, managing to achieve 74.0% of its recorded fuel economy. On paper it is capable of up to 70.6mpg, but of those owners who have submitted figures to HonestJohn.co.uk none have reported a figure higher than 55mpg. The Audi A1 fares little better and is fifth worst, managing on average only 46.8 miles to the gallon, a paltry 74.2% of its official consumption figure.

Land Rover may be responsible for one of the worst performing cars, but it is also responsible for the best, according to HonestJohn.co.uk: the Defender achieves 105.4% of its official test result. Second place is taken by the Toyota Celica with owners reporting 103.8% of its official consumption. The Jaguar S-Type also exceeds expectations, achieving an average of 33.3 miles to the gallon, 3.6% better than official figures permit. The nifty Nissan Micra K12 (2003-2010) and the Mercedes-Benz E-Class (2002-2009) finish third and fourth, achieving 102.7% and 102.1% of their official fuel economies, whilst the Honda Civic Type R (2007-2011) comes a close fourth with a Real MPG ratio of 102.1%.

While drivers might buy cars informed by official (laboratory tested) fuel consumption figures, the research shows that actual rates of fuel consumption can only be measured by assessment of engine performance in on-the-road mpg figures.

The publication of honestjohn.co.uk’s Real MPG means that consumers will be able to compare official figures with real user experience, helping them to make better informed decisions about their next car purchase.

Honest John, commented: "Real MPG is a great tool for car drivers to get a true sense of car performance. It’s significantly different from official figures, which could certainly be said to mislead consumers, but are the only figures car manufacturers are allowed by EC law to publicise. Rather than attack the EC figures, which are now the basis of car and company car taxation, we prefer to offer realistic figures achieved by real motorists to be used alongside official guidelines.

Given the ever-rising fuel prices, the Real MPG provides a tangible service for motorists. This information allows car owners and buyers to make accurate predictions as to how much fuel they will use, and be better prepared as to how much that will cost. It’s also important to remember that a car’s fuel economy does vary considerably due to several factors: driving conditions and driving style."

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