TL;DR: At today’s peak the Brisbane metro ULP median is 209.9 c/L, and the cheapest in town is 193.5 (Liberty Bellbird Park, out on the western fringe) — a 16.4 c/L gap. Is it worth the drive? The honest maths says: for a big gap, almost always. On a 50-litre fill in a typical 8 L/100km car, a 16 c/L saving is worth about $8, and the petrol you burn detouring — even at the dear local 210 c/L — only eats that saving after about 48 km of round trip. So you can drive ~24 km each way and still come out ahead on fuel alone. The catch is the small savings: a 3 c/L gap breaks even at under 9 km round trip, so it only pays if the cheaper servo is basically on your way. The fuel is rarely the reason not to go — your time is.
Someone asked me this in the servo queue, holding the nozzle: “there’s one 20 cents cheaper across town — is it actually worth driving there?” It’s a maths question with a clean answer, so here it is.
The two numbers that decide it
Driving to a cheaper servo is a trade: you save on the fill, but you spend fuel getting there. The break-even is just where those two meet.
- What you save = the price gap × how much you’re buying. A 16 c/L gap on a 50 L fill is 0.16 × 50 = $8.00.
- What the detour costs = the extra distance × your car’s thirst × the price of the fuel you burn. A car doing 8 L/100km, driving an extra kilometre, burns 0.08 L; at the dear local 210 c/L that’s about 17 cents a kilometre.
Divide one by the other and you get the distance where the trip stops being worth it:
break-even round trip (km) = (saving per litre × litres in the fill) ÷ (your car’s litres-per-km × the price of the fuel you burn)
For that 16 c saving: $8.00 ÷ $0.168/km ≈ 48 km round trip. Call it 24 km each way. Drive less than that and the cheaper fill still wins on fuel.
The break-even, by how much you’d save
Same 50 L fill, same 8 L/100km car, fuel burned at today’s dear 210 c/L. Here’s how far you can drive — there and back — before the detour eats the saving:
The shape is the whole lesson. A 15–20 cent gap — which is exactly what a cycle peak opens up — is worth a 45–60 km round trip on fuel alone. You will almost never drive that far for a fill, so at a peak the cheap servo is essentially always worth it if it’s anywhere near your day. But a 3–5 cent gap breaks even at 9–15 km round trip — under 8 km each way — so it only pays if the cheaper price is on a road you were driving anyway.
Why the fuel you burn barely matters
Here’s the counter-intuitive bit. People picture the detour “using up” the saving, but the petrol is tiny next to the gap. Burning a kilometre costs ~17 cents; the saving on a 50 L fill at 16 c/L is 800 cents. You’d have to drive nearly fifty kilometres to spend what you saved. The fuel is almost never the reason to stay home — the honest cost of a long detour is your time, and that’s a call the maths can’t make for you. Fifteen minutes each way for $8 is about $16/hour of your time; you know whether that’s worth it.
What changes the numbers
- A thirstier car helps less. A 4WD at 12 L/100km burns ~25 c/km, so its break-even distances shrink by about a third — a 16 c saving breaks even near 32 km round trip instead of 48. Still generous, but the gas-guzzler pays more to chase cheap fuel.
- A bigger fill helps more. Filling 70 L instead of 50 stretches every break-even by 40%, because the saving scales with litres while the detour cost doesn’t.
- The fuel price cancels out, mostly. We valued the burned fuel at today’s dear 210 c/L on purpose — that’s the worst case. If your tank’s still got cheaper fuel in it, the detour is even more worth it.
So what
At today’s peak the cheap end is real — 193.5 at Liberty Bellbird Park, a cluster in the mid-190s at Willawong, Eagleby and Clontarf — but those are fringe suburbs, a drive from the inner city. The maths says take the drive when the gap is big: a 15-cent-plus saving pays for a very long detour. When the gap is only a few cents, don’t cross town for it — grab it if it’s on your way, otherwise fill where you are. Pinly Fuel maps every station’s live price so you can see the gap and the distance before you decide.
How we measure: Brisbane-metro ULP from the QLD Government feed, 9 August 2026 — median 209.9, cheapest 193.5. The break-even maths uses a 50 L fill and 8 L/100km as a typical mid-size car; your own tank size and consumption shift the distances, and the figures value detour fuel at the dear local price, so they’re a conservative floor. Time isn’t costed — that part’s yours.