We assume that because it’s the cheapest per litre it’s also the most cost effective to run. Surprisingly that’s mostly not the case. I’ve seen many examples where premium fuel gets people much further, so they’re not only reducing their fuel costs with premium but also benefiting from using a superior fuel.
Unfortunately, it’s not the case for ALL cars. Engines come in all shapes and sizes so the best way to check is to run a test. I’ve given instructions for that test below but first let’s get rid of some of the mysteries around fuel types.
Fuel Options
Standard Unleaded Petrol 91 or E10: Most standard cars in Australia will have the ‘Unleaded Fuel Only’ sticker on the fuel cap. This means you can use Standard Unleaded Petrol 91 or E10. It has a mix of up to 10% ethanol and it’s the cheapest by the litre at the pump. If you have an older vehicle you should avoid using E10 as it can clog your fuel filter and injectors, quickly becoming an expensive problem to solve.
Premium 95 Octane Unleaded Petrol: This the cheaper of the two premium unleaded fuels available. It’s the one you use if your fuel cap says ‘Premium Unleaded Only’. Using E10 in these vehicles can cause serious and expensive engine damage.
Premium 98 Octane Unleaded Petrol: The most expensive petrol on the market, this premium fuel is required by many luxury and high-performance vehicles, as well as many cars with a turbo or supercharger. If your fuel cap says ‘98 Octane Unleaded Only’ then you must use 98 Octane.
E85 (bio fuel): This new fuel is only just coming into the market. It’s made from corn in most countries and produces fewer emissions, so it’s definitely the most eco-friendly choice. However you can only use it if your car has been released specifically for E85. Not only is it good to the environment, it’s also great for performance with most Group A Touring cars using E85. It seems a lot cheaper than other fuels per litre, however E85 vehicles use a lot more fuel, so you’ll be filling up more often and your overall spending will be about the same as everyone else.
Choosing your fuel
First and foremost you must follow your manufacturer’s recommendations. You can always use a higher octane (that’s the higher number) fuel but NEVER EVER a lesser fuel. Using E10, for example, on a Premium Unleaded vehicle is going to seriously damage your engine.
If however, your car is like most Australian cars and doesn’t specify a particular fuel (this is when it indicates simply ‘Unleaded Petrol Only’) then you get to choose if you want to go premium. It may seem more expensive at the pump, but it could actually be better for your engine and your fuel efficiency. Every car is different though, so the best way to decide is to test it.
The test
NOTE: The below test is only for standard vehicles with the manufacturer specification is ‘Unleaded Petrol Only’.
- When you next need to fill up, full your tank with regular unleaded and set your trip counter to zero. Take a note of how much the fuel was per litre and how many litres you put in.
- Drive around as you would normally.
- When you’re hitting empty, record the kilometres on your trip counter.
- To work out your fuel costs on regular unleaded, divide the kilometres driven by the litres used and then multiply this number by the cost of petrol. For example:
100km driven ÷ 10 litres fuel used = 10 litres per 100km
10 litres x $1.25 per litres of regular unleaded = $12.50 per 100km
Now you have the kilometre-per-litre fuel rating for your vehicle using regular unleaded.
- Repeat this process using premium unleaded and compare the difference in dollars per 100km to see whether your car is more fuel efficient on regular or premium unleaded.This is going to vary as fuel prices change, however what you should be able to calculate is the point at which the cost difference between regular and premium makes no difference to your overall fuel cost. Knowing this will help you decide which petrol to choose the next time you fill up — if your objective is to save money on fuel, that is.
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