TL;DR: The folklore is that E10 is the budget fuel — always a few cents under regular 91, grab it and save. I checked it against the feed. Across the 391 Brisbane-metro stations selling both today, E10 is a median of just 2 c/L cheaper than 91 — and at a handful it’s dearer (NightOwl BP Sunnybank: 91 at 199.9, E10 at 203.5, so E10 costs 3.6 c/L more). Here’s why 2 cents isn’t the win it looks like: ethanol carries about a third less energy than petrol, so E10 — a 10% ethanol blend — gives most cars roughly 3% fewer kilometres a litre. At today’s ~210 c/L that penalty is worth about 6 c/L. So a 2-cent price saving against a 6-cent economy cost is a net loss of about 4 c/L. E10 only wins today where the discount is 6 c/L or more (rare — the biggest gap I found was 8.9) or your car genuinely sips it. The cheap-fuel reflex is out of date.
“Just put E10 in, it’s cheaper.” Every servo, every mate with an opinion. It used to be reliably true — E10 sat a solid 4 to 6 cents under 91, and for a car that could drink it, that was free money. So this is a fair claim to audit, because prices move and folklore doesn’t.
What the feed shows
Every number here is the Queensland Government price feed — what each station reported charging today, not a guess. I pulled every Brisbane-metro station that lists both regular 91 (ULP) and E10 — 391 of them — and took the gap at each one.
The median gap is 2 c/L. Not four, not six. Two.
And the tail is worse than the median. At some stations E10 isn’t cheaper at all:
- NightOwl BP Sunnybank — 91 at 199.9, E10 at 203.5. E10 is 3.6 c/L dearer.
- NightOwl Shell Wakerley — 91 at 206.9, E10 at 207.9. E10 a cent dearer.
- Quill Petroleum — 91 at 199.9, E10 at 199.5. Four-tenths of a cent cheaper — a rounding error.
Two cents at the middle, and a real chance the “cheap” fuel is the dear one. That alone should retire the reflex. But the price gap is only half the audit.
The half nobody prices in: energy
E10 is ten per cent ethanol, and ethanol carries about a third less energy per litre than petrol. Blend it ten per cent and the fuel holds a few per cent less energy — which means a few per cent fewer kilometres out of every litre. Independent testing and the carmakers put the real-world hit at around 3% for a typical car (it varies — some cars barely notice, a few older ones can’t run E10 at all).
Three per cent doesn’t sound like much until you price it. If you burn 3% more fuel to go the same distance, that’s the same as paying 3% more per litre. At today’s ~210 c/L, 3% is about 6 c/L. So to actually break even, E10 has to be about 6 cents cheaper than 91 — not 2.
Here’s the audit in one picture:
The verdict
Busted — at today’s prices. For a typical car, E10 at a 2-cent discount is a roughly 4-cent-a-litre loss once you count the kilometres you don’t get. It only comes out ahead when the discount is genuinely big — 6 c/L or more, which today is rare (the widest gap I found was 8.9) — or if your specific car is one of the ones that barely feels the energy hit.
To be fair to E10, cost isn’t its only argument: it burns a little cleaner and supports the local ethanol industry, and if your car is happy on it and the gap is wide, take it. But the automatic “E10 = cheaper” is out of date. The saving that made it a no-brainer has been squeezed to two cents, and two cents doesn’t cover the tank you burn faster.
The better move is the same one that beats every fuel myth: don’t pick by the label, pick by the number in front of you. A 91 at a cheap independent will beat an E10 at the pack most days now. Pinly Fuel shows both, live, at every Brisbane station — compare the actual prices, not the reputation.
How we measure: the 391 Brisbane-metro stations listing both 91 and E10 on the QLD Government feed, 9 August 2026 — median price gap 2 c/L. The ~3% economy figure is the well-established energy penalty of a 10% ethanol blend, not a measurement from our feed; it varies by vehicle, so treat the 6 c/L as a typical-car rule of thumb, not a promise for yours. Check your owner’s manual before switching fuels either way.