Blog: could motorists be forced to pay millions more in tax to compensate for exaggerated efficiency figures?

The so-called ‘dieselgate’ scandal has dragged the world of economy claims into the limelight. It’s made front-page news within the mainstream media as prosecutors initiate fraud investigations and top VW bosses jump-ship quicker than you can say ‘TDI’.

It’s bound to have consequences – for Volkswagen Group, of course, but also ripple effects across the motoring industry.

The scandal affects NOx emissions from a range of VW’s turbodiesel engines. This is not the same as CO2 emissions or fuel economy figures.

It’s well known within the motor industry that cars never match their ‘claimed’ MPG figures during everyday driving. The figures are taken from the New European Driving Cycle (NEDC) lab-test that all cars are put through. We know that everyday figures are going to be lower (with fuel economy figures overstated by as much as a 74%, according to data released today by Professional Driver Magazine).

You may think this is unfair – that car buyers are duped into thinking they’re going to get much better fuel economy in real life than they actually do. But it’s unfair to blame car manufacturers entirely for this – the figures come from the official EU test, and if carmakers actually could make MPG claims they could potentially be very different.

What the official test is good for is comparing cars. For example, a 150hp Ford Mondeo TDCi returns 67.3mpg officially, while the equivalent Volkswagen Passat returns 70.6mpg. You won’t see these figures on the trip computer under normal driving conditions – but it’s fair to say the Passat should be slightly more efficient than the Mondeo.

There are calls for the test to replicate real driving conditions but this would be very difficult to do inside a lab. Using fuel economy figures taken from the road wouldn’t be scientific – there are too many variables. Cars need to be tested in the same weather conditions, at the same speeds to create a comparable economy figure.

Even the Society of Motor Manufacturers and Traders (SMMT) has admitted the fuel economy test is inadequate in the wake of the VW emissions scandal. In a press release issued last week, the organisation said: “On the separate on-going debate about real-world testing, industry accepts that the current test method for cars is out of date and is seeking agreement from the European Commission for a new emissions test that embraces new testing technologies and which is more representative of on-road conditions.”

But what could such a test mean for the general public, innocently driving our turbodiesel Volkswagens with no intention to cheat the planet?

“There is a direct link between fuel economy and CO2 emissions,” says Professional Driver editor, Mark Bursa. “That means all the cars we’ve tested are certainly emitting more CO2 than claimed. Some would certainly be in a higher tax band if real-world figures were used. The Government could be missing out on tax revenue as a result.”

And that final sentence worries me. The UK Government will be watching the Volkswagen emissions scandal closely, and it’s highly likely there could be repercussions across the board. This could be in the form of revised fuel economy and CO2 tests which, as well as indirectly costing taxpayers millions, could see the vast of majority of motorists having to pay more for CO2-based road tax. Should we be encouraging the Government to look more closely at fuel economy and emission claims when, ultimately, it’ll be us out of pocket?

More on the VW Group scandal on Motoring Research