Diesel prices have hit an all-time high, with forecourts charging an average of 199.18p per litre in the UK as of Monday, according to the RAC's latest petrol price checker. The cost of filling up a diesel car has never been higher, following weeks of painful price rises at the pumps.
In December 2025, diesel averaged 142.57p per litre, and the rises show no sign of abating as the war between the US and Iran continues. Since the beginning of September, the average cost of diesel has risen by around 16p per litre, adding roughly £9.60 to the cost of a typical 60-litre fill, according to Petrol Prices.
Expert tips to cut diesel costs
According to ClickMechanic, simple mistakes behind the wheel—from harsh acceleration to underinflated tyres—could significantly increase fuel consumption. Car expert Scott Greensmith has listed several tips to cut diesel bills at this critical time.
Stop using aircon
Air conditioning is a nice perk, even as temperatures drop, but Scott Greensmith says it ruins fuel economy. He said: "Air conditioning can reduce fuel economy by around 5–15%, so using it all the time isn’t always the most efficient option."
Inflate tyres correctly
Low tyre pressure increases resistance and forces the engine to work harder. "Keeping tyres properly inflated is one of the quickest and easiest ways to improve fuel economy. It also helps extend tyre life, meaning you save money in more than one way," says Scott.
Stop braking harshly
Rapid driving burns more fuel than necessary. "Driving more smoothly and anticipating traffic ahead can make a noticeable difference to efficiency," Greensmith said. "Constant stop-start driving and sudden bursts of speed force the engine to work harder, which uses more fuel over time."
Stop idling the engine
Sitting with the engine running wastes fuel, especially on short stops. "If you’re parked or waiting, switching off the engine can help avoid unnecessary fuel use. Even a few minutes of idling each day can quickly add up over the course of a week."
