E10 vs Unleaded 91: Which Fuel Should You Use?

Every time you pull up to a Queensland petrol station, you face the same choice: E10 or Unleaded 91? With E10 typically sitting 3 to 5 cents per litre cheaper, it looks like the obvious pick. But is the saving real once you account for fuel economy? Here is everything you need to know.

What Exactly Is E10?

E10 is a blended fuel that contains up to 10 per cent ethanol and 90 per cent regular unleaded petrol. The ethanol component is produced from plant-based sources, primarily sugarcane and grain. In Queensland, sugarcane-based ethanol is common, making E10 a partially renewable fuel option. It carries a minimum octane rating of 94 RON, which is actually higher than standard Unleaded 91.

Unleaded 91 (ULP 91) is the baseline petrol grade in Australia. It contains no ethanol and has an octane rating of 91 RON. It has been the standard fuel for Australian vehicles for decades and is compatible with virtually every petrol engine on the road.

Price Difference: How Much Do You Actually Save?

Across Brisbane and South East Queensland, E10 is typically priced 3 to 5 cents per litre below Unleaded 91. On a 50-litre fill, that translates to a saving of $1.50 to $2.50 at the bowser. Over a year of fortnightly fills, that adds up to roughly $40 to $65 in raw pump savings.

However, the sticker price does not tell the whole story. Ethanol contains about 34 per cent less energy per litre than pure petrol. In a 10 per cent blend, that works out to approximately 3 per cent less energy overall. Most drivers will see their fuel economy drop by about 1 to 3 per cent when running E10 compared to Unleaded 91.

The takeaway: when the price gap is 4 cents or more, E10 usually comes out slightly ahead. When the gap narrows to 2 cents or less, Unleaded 91 can actually be cheaper per kilometre driven. Checking live prices on Fuel Daddy before you fill up ensures you always pick the better deal on the day.

Engine Compatibility: Can Your Car Use E10?

The vast majority of petrol vehicles manufactured from 2005 onwards are designed to run on E10 without any issues. This includes popular models from Toyota, Mazda, Hyundai, Kia, Ford, Holden and most other brands sold in Australia. If your car was built after 2005, it is very likely E10-compatible.

Vehicles That Should Avoid E10

The following types of vehicles generally should not use E10:

• Cars manufactured before 2005 (check specific model compatibility)
• Some European vehicles, particularly older BMW, Mercedes-Benz and Volkswagen models
• Certain motorcycles, boats and small engines (mowers, chainsaws, generators)
• Vehicles where the manufacturer explicitly states "Unleaded 91 only" or "No ethanol blends"
• Classic and collector vehicles with original rubber fuel system components

If you drive around Sunnybank, Chermside or Carindale in a modern hatchback or SUV, E10 will almost certainly be fine. If you are driving a pre-2005 vehicle or something with a specialty engine, stick with Unleaded 91 to be safe.

Performance and Engine Health

For compatible engines, E10 will not cause any performance issues. In fact, because E10 has a higher octane rating (94 RON versus 91 RON), some modern engines with knock sensors may extract marginally better performance from it. That said, the difference is negligible for everyday driving.

One consideration is fuel storage. Ethanol is hygroscopic, meaning it attracts moisture from the air. If you leave E10 sitting in a tank for extended periods (more than a few months), it can absorb water and potentially cause corrosion or starting issues. This is most relevant for seasonal vehicles, boats, or cars that sit idle for long stretches. For vehicles driven regularly, this is not a concern.

When E10 Makes Sense

E10 is the better choice when:

• Your vehicle is confirmed E10-compatible
• The price gap is 4 cents per litre or more below Unleaded 91
• You drive regularly and do not store fuel for extended periods
• You want to support a partially renewable fuel source

When Unleaded 91 Is the Better Pick

Stick with Unleaded 91 when:

• Your vehicle is not approved for ethanol blends
• The price difference is less than 3 cents per litre
• You are filling equipment that sits unused for weeks or months (mowers, generators, boats)
• Your manufacturer specifically recommends non-ethanol fuel

Finding the Cheapest E10 and ULP 91 Near You

Fuel prices vary significantly between stations and suburbs. On any given day in North Lakes you might find E10 at 169.9 cpl at one station and 179.9 cpl just two kilometres away. The same variation applies across Ipswich, Redcliffe, Caboolture and the Gold Coast.

Use Fuel Daddy's E10 price map or Unleaded 91 map to compare real-time prices at stations near you. Combine smart fuel selection with timing the fuel price cycle and you can save hundreds of dollars a year.

Key Takeaways