Fuel types for cars and how they differ

Car makers always mention the type of fuel compatible with your car. If you don't know the recommended fuel to fill the car you're driving, you can check the owner's manual or inside the car's fuel cap. If you don't have the owner's manual and the text inside the fuel cap is scratched, another option could be calling your regular service centre and checking with them. 

If you're unsure, don't make the mistake of guessing the right fuel for your car. Mixing fuel types (filling up a petrol engine with diesel or vice versa) could damage your car's engine. You should also educate yourself about the different petrol and diesel variants on the market, as your vehicle is unlikely to be compatible with all the different variants.

Diesel typically comes in two varieties – regular and premium diesel. Premium diesel costs more than regular diesel, but whether it's better than regular diesel for your car's performance is debatable. According to Drive, the only difference between regular and premium diesel is the different additives package. While some fuel brands claim their premium diesel can keep your car's engine cleaner or healthier, it's unlikely you'll get any performance advantage by switching to premium diesel for your vehicle.

Some service stations also offer biodiesel blends for your car. B5 and B20 are becoming increasingly common and contain a combination of diesel with five or 20 per cent fatty acids derived from vegetable oils and waste fats, respectively. However, not all diesel vehicles may be compatible with biodiesel. You should check with your car manufacturer whether it's okay to use biodiesel in your car.

Biodiesel could be a more environmentally-friendly choice than regular or premium diesel, but any beneficial impact on performance and fuel efficiency compared to regular diesel isn't proven.

Different Research Octane Numbers (RON) are used to indicate the octane level of your fuel. The acceptable octane rating for regular unleaded petrol in Australia is 91. This type of 91 unleaded petrol is widely available and works well for most petrol cars unless you own a performance vehicle. A popular and slightly cheaper alternative to P91 is E10, which contains 10 per cent ethanol and 90 per cent unleaded petrol. Ethanol is a renewable fuel, typically produced from grains, sugar cane, or other plant materials.

Is E10 good for your car, however? The answer is subjective. E10 generally costs slightly less than P91, but it may or may not give you better performance in terms of fuel efficiency. Carsguide says that ethanol can help lift the octane rating of fuel, but it doesn't translate into higher performance or improved mileage. The alcohol content also increases fuel consumption due to the fuel's energy density, which means E10 might not take your car or truck further than if you used P91. However, E10 might be considered more environmentally friendly than standard petrol as it is known to produce lower emissions.

Most modern cars on Australian roads have E10-compatible engines. You can also use this compatibility checker provided on the NSW state government website to confirm whether your car can run on E10 or not.

Premium petrol types available are P95 and P98 with higher octane numbers. P95 can be used in most cars instead of P91 without causing any harm. However, if your vehicle specifically requires premium petrol, replacing it with low octane fuel can lead to knocking in the engine and damage. P98 is the most premium petrol type available and also the most expensive. It is mainly used in sports cars and performance vehicles. Your manufacturer might warn you against using P95 in a car that specifically requires P98 petrol. 

Another fuel type specifically designed for performance vehicles is E85, containing between 70 to 85 per cent ethanol mixed with regular unleaded petrol. E85 has an octane number of 105 and can only be used in cars specifically designed to use it, such as flexible-fuel vehicles and V8 racing supercars. Using E85 in a car not built or modified for it can damage the engine.

With fuel prices soaring across the country, it makes sense to look for ways to save money on the cost of fuel. One of the simplest ways to cut down your fuel costs is by walking, cycling or catching public transport when you can. Your car is also a contributor to the pollution in your city. By avoiding driving your car over short distances and carpooling when you can, you not only save money but also help the environment.

Unfortunately, it's not always possible to walk everywhere, and you'll sometimes need a car to get from A to B. Driving your vehicle the right way, using the correct type of fuel, and maintaining it properly through regular servicing and repairs are some simple ways to boost your car's performance and fuel efficiency. You could also save money by comparing different retailers' fuel prices.

Rising fuel prices have also led some people to wonder whether this is the right time to invest in an electric vehicle (EV). The official NSW Government site says that EVs are cheaper to run, helping you save up to 70 per cent of your fuel costs. EVs are also considered environmentally friendly, with the potential to significantly reduce greenhouse gas emissions. 

Swapping your old car for an energy-efficient EV could therefore help you significantly cut down your fuel costs. You’ll also earn some good karma for reducing your impact on the environment. However, EVs aren’t always the cheapest option on the market, and you might have to shell out more money than you would have paid for a fuel-based car with comparable features. As cost can often be a deciding factor when purchasing a car, remember to compare the purchase price of different models as well as the running costs to pick a car that meets your present and future needs. Even when you’re looking to finance your car, it could be worth comparing the different options available, including green car loan products that are offered to borrowers who intend to purchase an electric vehicle.