Scale of misleading fuel consumption figures revealed

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Motorists could be burning through as much as 75% more fuel than stated by car makers, according to new research by German technology company Carly.

The worldwide in-car app collected data from over one million vehicles, including 150,000 from the UK. The results show year-on-year growth of discrepancies in fuel consumption between official lab figures and real-world data in every new model generation between 2004 and 2016, followed by a slight reduction in 2017.

The most significant difference was found in diesel cars from 2016, achieving an average of 75% higher consumption rates than stated in information given by the vehicle manufacturer.

According to the RAC Foundation, the average given fuel consumption for a diesel car in 2016 was 62.5mpg. For a motorist driving 12,000 miles, this would be a cost of £1,087.55 per annum (based on current diesel costs of 124p per litre). Considering the discrepancies found by Carly, this figure could instead be £1,903.21, an additional cost to the motorist of £815.66 a year.

Overall, Carly uncovered discrepancies were greatest in the three most popular vehicle segments in the UK; small cars, compact cars and SUVs.

The Carly app found drivers of small cars are using as much as 55% more diesel and 35% more petrol than the official figures, adding hundreds of pounds to annual running cost budgets.

For compact car drivers, the real-life diesel consumption recorded as 45% higher than manufacturer figures, with the news no better in the increasingly popular SUV segment; burning through 45% more diesel and 40% more petrol than owners might expect. The only market segment where manufacturer data reflected real-world results was diesel sports cars where real-world figures reflected the official data (and let’s face it, a diesel sports car is a bit of an oxymoron anyway).

“There is an ongoing conflict of interest regarding fuel consumption. Over the years the regulations require less and less CO2 emissions, however; drivers want more powerful and luxurious vehicles,” says Avid Avini, one of Carly’s founders.

“With each new CO2 reduction strategy, manufacturers have had to reduce fuel consumption; however due to tests being carried out in laboratories rather than the real-world, the data shows consumption to be improving.

“Miles per gallon is one of the key concerns of UK drivers when buying a car, as ongoing vehicle running costs can have a huge impact on the monthly budget. While it can be difficult for manufacturers to predict consumption, as it is very much dependent on individual driving style, a discrepancy of this size is of concern to consumers relying on manufacturer figures.”

New fuel consumption and emissions tests coming into force in the UK will hopefully start to eliminate these massive discrepancies in the next few years, but used car buyers are likely to be stuck with inaccurate and misleading fuel consumption information for many years to come.

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Michael Dalton
Michael Dalton
Michael graduated from university in 2016 with a degree in Human, Social, and Political Sciences. He contributes to both The Car Expert and The Van Expert.

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