Motorists are paying up to £854 more on fuel a year because manufacturer miles per gallon figures are misleading, according to research by consumer magazine Which.
The report found claimed fuel economy figures were an average of 13 per cent short of the reality for 200 new cars tested between 2013 and 2014, costing drivers an average of £133 extra a year in fuel.
Just three cars out of the same 200 managed to reach their official fuel economy rating: the 1.2-litre Skoda Roomster, 2.0-litre Mazda 3 Fastback and the 2.0-litre, five-door Skoda Yeti diesel automatic. That means a whopping 197 cars underperformed.
Reasons cited by Which as to why there is such a large discrepancy include the outdated nature of the NEDC test, which was updated in 1997 but the basis was first introduced in the 1970s, and that manufacturers can choose an ‘accredited lab’ for testing.
The test also neglects to test for motorway speeds for longer than ten seconds and that the less thirsty’ eco’ mode of modern cars can actually be too unresponsive for actual roads so most people will never use them.
Not only that, tests can be performed with the air conditioning off and other equipment that would otherwise eat into fuel economy, a tolerance of 12mph below the required speed limit is allowed (yes, the test for 30mph would allow a speed of 18mph) and items can be removed to save weight such as the passenger door mirror.
Furthermore, tyres can be pumped up way beyond recommended pressures to reduce rolling resistance, there is no official body in place to monitor the results from lab to lab and – just to put the cherry on the very misleading pie – the rules allow manufacturers to knock 4 per cent off the results arbitrarily.
No wonder, then, it is easy to find complaints from owners of cars that really never get fuel efficiency near what is promised. The biggest offender in the Which? list is the Mitsibushi Outlander PHEV plug-in hybrid, which promises 148mpg but only manages 67mpg at best. That means its annual fuel bill doubles to £841.
It’s worth pointing out that, although the PHEV misses its target by 120 per cent, it is the most fuel efficient sports utility vehicle Which? has tested, as part of its rolling road lab test designed to be indicative of real-world driving conditions.
Which? executive director Richard Lloyd said: “The cost of fuel is one of the biggest concerns for consumers which is why fuel efficiency has become an important selling point for new cars. The new test should be brought in without delay so consumers are no longer misled by fantasy mpg figures.”
The new test will take time to be implemented. It largely depends on how long the European Commission takes to draft up the new test and how long it takes national governments to sign it off. So for now the flawed NEDC test cycle will remain in use in Europe.
“Which? thinks that they should reflect the real results and we want carmakers to implement the new test as soon as possible. We will be working with the other European consumer groups to keep up the pressure,” the report added.
One motorist won a legal case against a dealer because the car he was sold failed to match the fuel economy he had been promised and that the dealer has specifically asked about fuel efficiency at the point of purchase. The car was, therefore, deemed not fit for purpose under the Sale of Goods Act and the dealer had to issue a full refund.
If fuel economy is a big concern, it might be worth checking out the experience of motorists who already own the car you are looking at so there are no surprises. Or save a few extra pennies while manufacturers are economical with the truth with this handy guide.
Do overly-enthusiastic fuel economy figures grind your gears? Is it time we ditched the old test? Let us know in the comments.