Do you ever feel that your car burns through a tank of fuel at a much faster rate than you expected?
If so, you’re not alone. We’ve found that medium-sized petrol engine cars from the likes of Alfa Romeo, Volvo and Audi can be as much as 29% less fuel efficient than the official MPG figures used by manufacturers in their advertising.
In fact, only medium cars from five brands – Hyundai (3%) and Kia (5%) – came within 5% of the more accurate MPG results achieved through our expert lab testing.
EU law requires carmakers to show official test figures in their adverts to help consumers compare fuel economy between different models. But we think the figures should also reflect real-world driving – and if a brand quotes an MPG figure in its adverts, a consumer should be able to achieve it in normal use.
That’s why it’s vital the EU test is updated to be more accurate in 2017 as planned, and not delayed to 2020 as some manufacturers would prefer.
Come clean on fuel claims – sign our petition for fuel claims you can trust.
Petrol engine medium cars – claimed vs actual miles per gallon (% difference)
Which cars were included in the study?
The medium cars category is an industry-standard class including the likes of the Ford Focus, Audi A3, Peugeot 308, Seat Leon, Volvo V40, Volkswagen Golf, Alfa Romeo Giulietta, Renault Megane, Mercedes-Benz A-class, Honda Civic, BMW 1 Series, Hyundai i30 Tourer, Skoda Rapid Spaceback and Kia Pro-Cee’d.
How we test MPG
The testing that underpins every Which? car review is designed to give consumers the most accurate picture possible of how their car will perform in everyday life. So when assessing fuel economy, unlike the official EU test, we include a motorway driving simulation, switch on the lights and air con, and inflate tyres to the recommended pressures.
And if a car has different driving modes available, we use the one it starts up in by default, rather than switching to an ‘eco’ mode. This may offer better economy, but will also often neuter a car’s performance to the point where it’s awful to drive.
What’s the problem with EU MPG measurements?
Don’t be fooled by the name of the official driving simulation currently used to calculate mpg figures – the New European Driving Cycle (NEDC) hasn’t been new since it was last updated in 1997, and the basis of the test was first introduced in the 1970s.
The test’s lack of real-world driving scenarios and numerous loopholes make the figures it generates unachievable when you get behind the wheel of a car.
Update: This page was corrected on 26th June 2015 to fix an inconsistency in the MPG data displayed in the graphic.