Discounts on new diesel cars are 25.6% higher on average than for their petrol counterparts, according to new data.

As the Chancellor looks set to penalise diesels further in this week’s Budget (Nov 22), analysis of What Car’s Target Price – a tool that calculates the most you should pay for any new car – shows the average saving on new diesels stands at £2,716.

What Car’s consumer editor Claire Evans said: “The dramatic rise in discounts is a direct response to a slump in demand caused by the Government's demonisation of diesels and a lack of understanding from consumers of the new cleaner ‘Euro 6’ diesels now available. It’s a perfect storm.”

The gap between petrol and diesel discounts is at its starkest in the volume sector (with a 34% bigger discount on diesels) and large SUVs (28%).

The biggest percentage discount available on a diesel is 25.2% off a Volkswagen Jetta 2.0 TDI 150 GT DSG saloon. Overall, target price savings climb as high as £22,626. 

Sales of diesel cars fell by 29.9% in October, compared with the same month in 2016.

Evans said: “At the current level of discounts available, any increases in tax on diesels will be off-set by the fall in price of the vehicle itself.

"For the canny buyer, the market is ripe for deals and securing big savings over petrol variants.

“Despite recent headlines, diesel cars still have much to offer, especially for drivers doing high annual mileage or a lot of motorway driving.

"They deliver better low-end power and more torque than petrol equivalents, so are much better suited to tasks such as towing, too.”