How much could comparing prices actually save you in a year?

Take an average driver filling up roughly once a week, around 45 litres each time, so about 2,340 litres across a year. Prices between nearby stations routinely differ by 10 to 20 cents a litre at the same moment. Even landing on the cheaper side by a modest 8 cents a litre on average adds up to well over 180 for the year, from doing nothing but glancing at a map before you pull in.

Drive more, and the number grows with it: a higher-mileage driver filling up twice a week can be looking at 300 to 400 or more, purely from consistently picking the better-priced pump nearby, no different driving, no different car.

Brand and loyalty discounts. A few cents per litre off a card you already carry adds directly to the saving above, for zero extra effort once it is set up.

Skipping the wrong detour. A cheap price far away can quietly cost more once you count the fuel to get there. Counting that correctly protects the saving instead of accidentally cancelling it out.

Avoiding captive prices. Motorway services and running low on a journey both push you toward whichever pump is in front of you. Planning ahead keeps you out of that trap on top of everything else.

None of this requires driving further or buying anything. It requires knowing the real prices around you at the moment you are about to fill up, which is the one piece of information a habit or a familiar pump cannot give you. Ten seconds of comparing is the entire cost of the saving above.

Is an 8 to 10 cent gap really that common?

Yes, in most cities a spread of 10 to 20 cents a litre between nearby stations at the same time is routine, not exceptional. The saving above uses a conservative slice of that range.

Does this still work if I drive very little?

The total is smaller with fewer fill-ups, but the per-litre saving is exactly the same. Comparing costs nothing extra either way, so it is worth doing regardless of your mileage.

Do I need to change stations every time?

No. You just need to know which nearby station is cheapest right now before you commit, and go there instead of the default one out of habit.

Does any of this work if I always use the same station?

That habit is usually where the money goes. A station that was the cheapest on your route two years ago is under no obligation to still be, and almost nobody re-checks. The point is not to chase every cent, it is to notice when your default has quietly drifted to the expensive side of the street.

Is this worth the effort on every single fill?

No, and nobody does that. The saving comes from the fills where you were about to make an expensive choice without knowing it, usually somewhere unfamiliar or when you are running low. Ten seconds before you pull in, on the trips where you do not already know the answer, is where the whole number comes from.

Two stations a kilometre apart can charge very differently for the same diesel out of the same refinery, and none of the reasons are about quality. Rent is the biggest one: a forecourt on expensive land has to earn that land back through the pump. Volume is the second, because a site selling four tankers a week can live on a thinner margin per litre than one selling a single tanker. Then there is what the place is really selling. Some forecourts are shops with pumps attached, priced to pull you inside; others have no shop at all and compete on the number alone.

Competition does the rest, and it is intensely local. One unbranded station pricing aggressively drags every pump within sight of it downward, while a stretch of road with no alternative for ten kilometres stays high. That is why the saving is repeatable rather than lucky: the gaps are structural, they sit in the same places week after week, and all you need to capture them is to know which side of the gap you are about to drive into.

The size of the prize depends on what goes into the car. Diesel and petrol spreads between neighbouring stations tend to sit in a similar band, so the yearly figure above holds for both. What changes is the rhythm: a diesel driver covering long distances fills less often but takes more litres each time, which lands in roughly the same place by the end of the year.

Electric is a different shape entirely. The gap between charging at home overnight and using a rapid charger on a motorway is not ten or twenty percent, it can be three or four times the price per kilowatt hour. For an electric driver the annual number is dominated by how much charging happens at home, not by which public charger gets picked. Get that ratio right and the public price barely matters; get it wrong and no amount of comparing will rescue it.