New research published by Transport & Environment (T&E) concludes that the average diesel car may produce more CO2 over its lifetime than a comparable petrol-engined vehicle, reversing the accepted position of emissions analysts.

The new results take into account factors such as well-to-wheel fuel emissions and vehicle production, as well as the higher average mileage covered by diesel cars compared to petrol models.

In total, the average diesel is predicted by T&E to produce 42.7 tonnes of CO2 over the course of its 113,000 mile lifetime, compared to petrol’s 39.0 tonnes during 109,000 miles, an increase of 3.7 tonnes which roughly represents a year’s motoring by an average car.

With diesel’s already recognised poor air-quality performance (including vehicle emissions such as NOx and PMs), if true, countering the fuel type’s lower CO2 emissions removes one of the few attributes going for the fuel.

T&E criticises European governments for creating a diesel dominated market in the region, which is in stark contrast to the rest of the world where diesel sales are relatively niche.

Across the EU, the last two decades have seen a large number of incentives for diesel, such as lower diesel fuel duty and company car tax benefits, which have together pushed diesel car sales to levels not seen in any other region. 70% of all global diesel car and van sales are now in Europe with the rest of the world only representing 7% total sales.

In the UK a similar picture emerged, though diesel sales until recently have for the past few years settled down at a little over half the new car market. In the past few months though, diesel sales have declined dramatically as the VW Emissions Scandal and concerns over air pollution have eroded consumer confidence in the fuel.

At the same time, improvements in petrol engine technology, hybrid powertrains, and increased choice of plug-in models has seen increases in market share, with alternatively-fuelled cars the greatest beneficiaries of diesel’s decline.

Read more: Next Green Car