The recent VW defeat device scandal blew the lid on car makers fudging the figures for diesel car exhaust emissions. But recent reports are indicating that the diesel emissions scandal is only half the story. By Jeremy Torr

Since 2001 official carbon dioxide (CO2) emission levels for new European passenger cars - both petrol and diesel - have decreased by an impressive average of 29%. That’s great news for the air we breathe.

But those official CO2 emission values are determined by EU sanctioned laboratory tests. And as recent analysis by the International Council of Clean Transportation (ICCT) has discovered, there is a significant and increasing gap between real-world emission levels and those impressive official values. And it is getting worse.

“[our] ... analysis shows that, in the EU, the gap between official and real-world CO2 emission values continues to grow—from 9% in 2001 to 42% in 2015,” said the ICCT in a recent report. If this sounds like scaremongering, here’s something to consider: the ICCT has many world class scientists on its books and was the key player in discovering the notorious VW ‘diesel defeat’ devices.

Dramatic increase in error reporting

ICCT’s Dr Peter Mock put it bluntly in a recent interview with the BBC. “The difference between official CO2 numbers and fuel consumption numbers, and the real world data from customers … is becoming bigger and bigger,” he says. “We see that in real world terms, the CO2 and the fuel consumption of vehicles is about 42% higher than what manufacturers claim it is.”

Mock says the majority of car makers are gaming the emissions test system in the EU, and producing figures that selectively indicate lower emissions than those produced by real world driving. He claims that “… almost 100% of the [reported lower emissions] effect is due to loopholes that are being exploited more and more over time.” According to Mock, manufacturers are “cherry-picking” the best test results from different EU countries, as well as using different cars of the same model to get the required pass levels for different emissions. And all quite legally.

“First of all, it is possible for the manufacturer to test the vehicle separately on air pollutant emissions, [then] on CO2 and fuel consumption,” he told the BBC. “So that means you can have one vehicle that is especially prepared just for CO2 emission testing, and it can have very high air pollutant [NOx] emissions. But nobody cares about that in the [CO2] test.”

Mock added that this loophole in EU regulations allows manufacturers to carry out the two critical tests (CO2 and NOx) independently. He also hinted at worse skulduggery by manufacturers. “We haven’t found an illegal defeat device … yet,” he added, “but it could also … be possible that for some vehicle models that there is also an illegal defeat device involved for CO2. But we don’t have any proof yet.”

Kidding ourselves on emissions

It’s not just the ICCT waving a warning flag on supposedly cleaner petrol vehicles. UK-based independent testing organisation, Emissions Analytics (EA), has warned that encouraging official EU data has given a misleadingly positive impression of the trend towards lower vehicle emissions.

“In recent years, we have been kidding ourselves about our actual achievement in reducing CO2 from cars,” said Nick Molden, CEO and founder of EA. “The new official world harmonised [emissions] test will help close the gap, but only partially,” he added.

Molden said that the dieselgate scandal in the US – primarily affecting VW, but with a knock-on effect to many other manufacturers – would “lift the lid” on the contentious EU testing regimes. “This is in many respects a much greater scandal [than dieselgate in the US],” he added.

Molden asserted that in the UK, the average tested vehicle is some five times the stated emissions limit, with others being up to twenty times the limit – and that  incredibly, none of the manufacturers are breaking the law. “That’s the scandal,” he told the BBC. “It is amazing how you can get round the official system in Europe by fairly simple strategies, and … most of [the car makers] have done that.”

Using his company’s tested figures for greenhouse gas emissions, and taking the car market as a whole, EA reports that average real world emissions of Euro6 cars are 181g/km of CO2 – a figure that hasn’t improved since the first Euro5 certificates were issued in 2011.

“Compared to the current legal fleet average [emissions] target of 130g/km of CO2, our new EQUA data shows this … target is being exceeded by 39%,” said EA in a recent report. Even more worryingly, only around 40% of EU-tested vehicles are within the company’s “most accurate” rating for real-world confirmation of the EU’s rated test. That means 60% of newly tested and certified cars in the EU are exceeding the legally mandated emissions limits in some way or another.

“Despite the recent controversy over manipulated NOx emissions,” says EA in its report, “it underlines the fact that the manufacture of more petrol powered vehicles, to address environmental concerns, could negatively impact CO2 pollution levels.”