Everyday Enviro with Elise: parsing through the best petrols

Everyday Enviro with Elise: parsing through the best petrols

By Elise Catterall  August 3rd, 2022

There are a lot of different types of petrol for non-electric vehicles and it's not simple finding out the most sustainable option at the bowser. This week, Elise delves into the best options for your car and the environment. 


It will be a much better world when everybody is driving an electric car, but until then most cars will be internal combustion engine cars that require petroleum to fuel them. But, if you’re like me, when you're standing at your local service station bowser and you’re looking at all the options for petrol (unleaded 91, unleaded 95, unleaded 98, and E10 - maybe even E85) you have no idea of the best option for the environment.

Generally speaking, unless you have a high-performance car, any of those types of fuel will be safe for your car and there will apparently be little tangible difference in performance. The key difference in the types relates to the octane number. The higher the octane number (Research Octane Number or ‘RON’), the greater resistance to ‘knocking’. Knocking is when an engine ignites before it should and can cause engine damage.

In Australia, regular unleaded petrol (RULP), must be a minimum 91 RON. RULP is the most common fuel type and is also usually the least expensive. It’s also the one that most cars are designed to run on. Premium unleaded petrol (PULP), must be a minimum 95 RON, but can also be up to 98 RON. These are more expensive fuel types recommended for fuel efficient, high-performance engines.

There is a perception that PULP is the better unleaded petrol - for both cars and the environment - but really that is only because it is designed for newer, and high performance cars, which are typically more fuel efficient. For a standard car, higher octane fuel doesn’t clean your engine or prevent engine deposits, it doesn’t outperform octane 91 and it also doesn’t provide greater fuel economy. It also isn’t less polluting than octane 91. So spending the extra money has no real benefits.

Then we have E10, which is an ethanol-based fuel with a blend of 10 per cent ethanol and 90 per cent unleaded petrol (either RULP or PULP), which is 94 RON. Though it has minimally lower fuel efficiency (due to a 3 per cent increase in consumption) compared to 100 per cent RULP and PULP, it is still considered the better option for the environment. There are several reasons for that.

One of the main reasons for this is that it is based on renewable biomass from plant products rather than 100 per cent non-renewable crude oil. The manufacturing process for ethanol is far less damaging than for petrol and E10 it has been found to reduce particles emission by up to 30 per cent compared with RULP. Then, there is the reduction in C02 emissions, which is estimated to be up to 5 per cent lower than RULP.

High performance cars (and some others) aren’t designed for E10, but pretty much all standard cars manufactured within the last 25 or so years will run well on it. Not to mention, it is also one of the least expensive options.

As a side note, E85 is another ethanol-based fuel that you might see and it has a blend of 85 per cent ethanol and 15 per cent unleaded petrol, which makes it probably the most environmentally friendly of all, but it is not widely available and currently is reserved for specialised cars.

Planet Ark does not take responsibility for the accuracy of the original information and encourages readers to check the references before using this information for their own purposes.


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Elise Catterall

Elise is a writer, photographer, and naturopath with a passion for nature. She completed a Master of Public Health in 2017 through the University of Sydney. Her photographic work focuses on flowers and plants as a way of celebrating nature. She has been writing for Planet Ark since 2017, sharing positive environment stories, personal environmental experiences and perspectives.

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