The battle against diesel cars continues, with London's T-Charge in full force and several councils raising parking charges for diesel cars. But motoring groups are calling for a rethink after a study by Emissions Analytics found some diesel models actually emit less toxic nitrogen oxides than some petrol cars.
Emissions Analytics is a testing company that helped expose the health threat from diesels, but its latest findings raise questions about indiscriminate charges on diesel vehicles.
As an extreme example, the cleanest diesel vehicle Emissions Analytics tested was a 3.0-litre BMW 5 Series. It emitted a mere 23 milligrams of NOx per kilometre – only around a quarter of the legal limit of 80mg/km.
In contrast, the 1.2-litre petrol Renault Kadjar emitted 130mg/km under testing, 50mg/km over the legal limit and six times as much as the diesel BMW.
While the findings aren't necessarily representative of the majority of vehicles on the road, it found that the cleanest 10 per cent of diesel cars emit 70mg/km of NOx on average, while the dirtiest 10 per cent of petrols emit 129mg/km.
Nick Molden, founder of Emissions Analytics, said the findings showed it was wrong to demonise all diesel cars, and lent weight to calls by motoring groups to the Chancellor Philip Hammond not to target diesels in this week's Budget.
"These real-world findings cast doubt on blanket taxes on diesels being the best policy," he said. "It makes no sense to punish or tax diesel as a technology per se, just dirty cars whatever their type."