An independent emissions study has found the cleanest new diesel engines on sale in post-Dieselgate world come from, err, Volkswagen.
Just over a year since Volkswagen’s €20 billion 'Dieselgate' emissions-cheating scandal broke to a stunned the car-making world, a Transport & Environment study has found the German volume brand’s newest cars to be the cleanest in the world.
While its Euro 5-compliant diesel cars are the dirtiest, the new technology it used to meet Euro 6 regulations have turned around the cheater brand’s performance.
The diesel-powered Volkswagens analysed in the study still emitted double the EU 6 standard’s maximum figure of 80 grams of NOx per 1000km in real-world testing, but that paled into insignificance alongside its market rivals.
The Transport and Environment study combed through data from a large public database as well as post-Dieselgate investigations from the French, German and British governments and found the diesel-powered cars from Fiat and Suzuki emitting up to 15 times the legal limit.
Renault and Nissan diesels emitted around 14 times the limit, Opel 10 times the maximum and Hyundai almost eight times the EU6 limit.
One massive shock was premium brand Mercedes-Benz emitting more than six times the legal limit, with the real-world emissions boosted by its use of “thermal switches” to turn off its exhaust-gas recirculation emissions-cleaning technology below 10 degrees and above about 26 degrees, ostensibly to preserve the integrity of the system.
Opel, Renault and Nissan all use similar software-operated thermal switching strategies, but turn off at 17 degrees.
Besides Volkswagen, the next cleanest diesel brands in Europe were Seat, Skoda and Audi (all Volkswagen Group badges), BMW, Mini and Mazda.
“This cannot be claimed as evidence of the Volkswagen Group learning its lesson; the Group brought its Euro 6 cars to market ahead of the Dieselgate scandal being exposed,” Transport and Environment’s Clean Vehicle Director Greg Archer noted.
“The Volkswagen Group’s Dieselgate engines were mostly of the EU5 generation.”
Shockingly, the study found that 80 per cent of EU5-compliant diesel cars and two-thirds of the EU6 diesels on European roads still emit at least three times the legal limit in real-world conditions.
“Dirty diesel cars are failing to operate their exhaust after-treatment systems for most of the time the car is driving, almost certainly illegally misusing a loophole in the rules governing the use of Defeat Devices,” Archer claimed.
“This is done partially to improve official fuel-economy figures but also due to doubts about the durability of the emissions treatment systems car-makers have chosen to use.
“The excessive nitrogen oxides emissions that result are the principal cause of the high levels of nitrogen dioxide in cities that led to the premature death of 72,000 EU citizens annually.”
Nevertheless, the report found many models met the current EU 6 regulations in real world testing, indicating that the technology to actually deliver clean diesels was available to those willing to invest in it.
They include Audi’s Q7 3.0-litre TDI, BMWs like the 318d, the X5 xDrive30d, the X1 xDrive20d, the 218d, the 220d and the 118d, the Ford Fiesta 1.5 TDCi and Ecosport 1.5 TDCi, the Citroen C4 Cactus 1.6 BlueHDi, the DS5 1.6 BlueHDi, the Peugeot 208 1.6 BlueHDi, the 308 2.0 BlueHDI, the Mercedes-Benz C200d, Mazda’s Mazda2 1.5d, the CX3 1.5d and CX5 2.2d and Volkswagen’s Golf Sportsvan 2.0 TDI.
Fully half of Europe’s tens of millions of “dirty” non-compliant EU5 engines in the real world tests come from just five brands. Volkswagen is responsible for 3.6 million of them, Renault for 2.4 million, Peugeot for 1.9 million and Citroen and Audi for around 1.8 million each.
Yet that table changes enormously on the real world figures for EU6-compliant models, with Renault and Mercedes-Benz clearly the worst.
Worst EU5 emitters Number of cars Worst EU6 Number of cars
Volkswagen 3,610,000 Renault 699,000
Renault 2,407,000 Mercedes 620,000
Peugeot 1,870,000 Peugeot 464,000
Citroen 1,806,000 Volkswagen 446,000
Audi 1,799,000 BMW/Mini 410,000
Mercedes 1,605,000 Citroen 379,000
Audi dropped from being the carmaker with the fifth-most non-compliant EU5 cars in real world testing to just 13th on EU6 figures and Volkswagen went from a clear first to fourth, while Mercedes-Benz climbed from sixth to second under the newer, tighter regulations.
Archer insisted that European nations and their Transport departments, which issue type approval for new models which is then accepted by other nations, are just as culpable as the car-makers themselves.
“The claim by car-makers that they are allowed to turn down the exhaust controls when the car is driven on the road (and operate them fully during a test) is a gross misrepresentation of the regulations and such a practice is almost certainly illegal.
“The regulations are clear that the emission-control systems should work fully during vehicles’ normal use. Carmakers are required to provide type approval authorities with information on the operating strategy of the exhaust treatment system.
“National type approval authorities have turned a blind eye to the use of defeat devices leading to such widespread health and environmental impacts.”
“Car-makers ‘shop around’ for the best offer from the regulators that compete among themselves for type-approving business.
"Some, approval authorities KBA in Germany, CNRV in France and MIT in Italy, protect their national car-makers and shy away from scrutinising them too strictly. Others, like the VCA in the UK, RDW in the Netherlands or SNCH in Luxembourg see type approval as a lucrative business,” he condemned.