Plummeting sales of diesel cars are likely to be hit even more by the introduction of extra taxes in the Budget later this month, according to the Financial Times.

The paper reports that Government aids have said the Chancellor of the Exchequer, Philip Hammond, believes a levy on new diesel cars is the best route to meeting budget requirements set out by the Clean Air Plan, which was published in May this year.

Under the plan, the Government would ban the sale of exclusively petrol or diesel cars by 2040.

The fresh tariffs for diesel cars – assuming they’re confirmed when the budget is announced on 22 November – will signal a further blow to diesel fuel, following figures released this week that revealed sales of new diesel cars were down 29.9 per cent last month compared to October 2016.

Commenting on the reports, RAC chief engineer David Bizley said: “We might be just over 20 years from the Government’s own deadline for ending the sale of new diesel and petrol vehicles, but it seems intent on dissuading as many of us from opting for diesel as possible.

“We are concerned that those who drive long distances, business drivers especially, might consider sticking with their older diesels given the superior economy they offer. It would be a terrible misjudged ‘knee-jerk’ reaction which could backfire and have the unexpected effect of encouraging these owners of older diesels and fleets not to upgrade to newer, cleaner diesels which offer significant benefits in reduced emissions.

“This isn’t what the Government, or any of us, want and is the opposite of what is needed from an air quality perspective. However, it would also be grossly unfair to penalise owners of current diesel vehicles.

“The irony is that the next generation of diesel engines which manufacturers are developing right now are likely to be as clean as their petrol equivalents - so while a new tax might be logical in the short term, this logic will likely not apply within a year or so.”