Motorists have been urged to top up their petrol and diesel vehicles at specific times of day, with road users likely to save money. William Fletcher, MBE, CEO of Car.co.uk has warned visiting petrol stations in the early morning or late at night could pay off.
The expert explained that it was better to fill up their vehicles “during the coldest parts of the day” when fuel is denser. As petrol pumps measure by volume, colder, denser fuel can mean road users get more for the exact same price.
William explained: “There's also a lesser-known benefit to filling up during the coldest parts of the day, early morning or late at night. Fuel expands in warmer temperatures, so you're technically getting slightly more petrol or diesel for your money when it's cooler and more dense.”
William isn’t the only one to suggest filling up vehicles at certain times of the day could be beneficial, with Money Saving Expert Martin Lewis suggesting motorists could get a “tiny bit extra” by heading to petrol stations at night. However, the Money Saving Expert founder reveals that any benefit is set to be “minuscule” with road users only saving “pennies”
Martin previously explained: “Talk of filling up at night getting you more is a slight urban myth, as the difference is minuscule pennies at best. Fuel pumps are calibrated by volume, so fill up at night when it's colder and you get a tiny, tiny bit extra."
However, experts at the RAC seemed to suggest claims that filling up fuel tanks in colder temperatures would benefit road users economically may well be a myth.
The RAC said: “There's not really any good evidence that shows it's cheaper to refuel at night.”
Meanwhile, petrol stations tend to store their fuel in a large and insulated underground tank which usually maintains a constant temperature regardless. This means the fuel density change between day and night may not be as drastic as many believe.
Fuel prices have dipped in 2026, with petrol and diesel costs declining from the start to the end of January, according to RAC Fuel Watch.
Petrol costs dipped from 135.28p per litre to 131.91p per litre in January, with diesel falling from 144.18p per ltre to 140.97p per litre.