The average price of a litre of diesel has fallen below 170p for the first time in 11 months.
Figures from data company Experian show UK forecourts were charging an average of 169.9p per litre on Monday.
It is the first time the price has been cheaper than 170p since March 9 2022.
The price drop means the cost of filling a typical 55-litre family car with diesel has fallen from the record high of £109 in June last year to £93.
RAC fuel spokesman Simon Williams said: “This is good news for drivers of diesel vehicles as they have had to endure some tough times, with the average price of a litre nearly hitting £2 at the end of June.
“Since then the price has tumbled 30p, saving more than £16 on a full tank.
“But, if retailers play fair with drivers, the price should fall further still as the wholesale price is now back to a level last seen around the time Russia invaded Ukraine.
“Even with retailers taking a higher-than-average margin of 10p a litre, the price of diesel should really be 10p lower at 160p.”