Environmental groups believe that diesel cars and trucks will be targeted by the government in order to drive down Britain's nitrogen dioxide (NO2) emissions.

The Supreme Court has ruled that the Department for the Environment must submit new plans to reduce NO2 emissions by the end of the year. In order to cut NO2, the DfE may be forced to take radical steps.

Freight operators believe that diesel vehicle owners will be incentivised to change to more environmentally friendly options – or face increased taxes.

There has been criticism from some quarters over the pro-diesel policies of the previous administration, which changed vehicle excise duty to penalise vehicles that emitted high levels of carbon dioxide. Diesels produced 20 per cent less CO2 than petrol engines, and so attracted less of the tax.

The so-called 'dash for diesel' prompted a nationwide rise in diesel vehicles from 1.6 million to more than 11 million in the last ten years.

While it is unclear how the Department for the Environment will tackle NO2 emissions, it appears as if diesel vehicles may be in the firing line.

Exactly how diesel owners will be incentivised or compensated is not yet clear.

Businesses that operate diesel vehicles have expressed hope that any scrappage scheme will make moving across to the greener options affordable.

The Supreme Court ruling was welcomed by Asthma UK, the British Heart Foundation and Friends of the Earth.

The motor industry has also voiced its support for greener car technologies. Mike Hawes, chief executive of the Society of Motor Manufacturers and Traders (SMMT), said: "Industry recognises the issues around air quality and is keen to see policy that reflects the progress made on vehicle emissions and wider challenges of CO2 reduction."