Cars and their fuels

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The fact that the majority of cars worldwide use petrol is inherently linked with the introduction and development of the car. Petroleum - refined from oil - became widely available and provided car manufacturers a potent fuel. However, factors are moving society towards alternate fuels, including the desire to be cleaner and greener, and to reduce our reliance on oil.

Oil-based fuels: Petroleum and more

Petroleum and the motor car redefined transportation, making it more efficient and more affordable as welli. In 2012, 81% of the vehicles in Australia ran on petroleumii. Over the years cars have become more efficient, making better use of our petroleum-based fuels.

Unleaded petrol is numbered according to an octane rating (RON). The higher the number the less chance of 'knocking' occurring.

The petrol we use in our vehicles, however, has changed with time. In 1921, General Motors research labs found that a tetraethyl lead additive to petrol was one way to eliminate "engine knocking" - a sharp sound caused by an uncontrolled explosion of fuel in the engine cylinderiii. "Knocking" makes the vehicle less efficient and can cause engine damageiv.

Unfortunately, the fumes released when burning leaded petrol are not only damaging to the environment, but also poisonous. By 1986, in Australia, the majority of car manufacturers made vehicles that could perform on unleaded petrol (ULP)v. Since the phase out of leaded petrol, oil companies have managed to develop alternative additives to increase the octane rating of their petrolvi. The higher the octane number, the less chance of “engine knocking" occurring, and the better the performance of the cariii.

Petroleum mixed with ethanol (produced from a variety of agricultural cropsvii) is one alternative in Australia that is already in production and useviii. E10 is a mixture of unleaded petrol with 10% ethanol and many vehicles currently on the road can use itix. However, with a low percentage of ethanol, the rising and falling price of oil is still a major factor in running costs. More recently, car manufacturers such as Holden, Bentley and Saab have been working to make their cars compatible with E85 (a blend of unleaded petroleum and up to 85% ethanol)x.

In addition to petrol, LPG- and diesel-based cars are present on Australian roads. Diesel, a derivative of petroleumxi, can offer fuel consumption advantages over petrolxii. However, exhaust emissions released from diesel engines are still harmful to human health and the environmentxiii. LPG (Liquefied Petroleum Gas) contains fewer toxins and produces lower greenhouse gas emissions per litre of fuel compared to petrolxiv, but vehicles of similar type will likely use more LPG than petrol over the same distancexiv.

Ranging from hydrogen and dung to electricity to solar, who knows what the standard fuel of the future will be?

Alternative fuels

In addition to making petroleum- and diesel-based vehicles more efficient, car makers have sought to find alternate fuels for our cars. Factors leading them to these alternates include a concern over petroleum suppliesxv, worsening air pollution due to greenhouse gas emissions from vehicles, and a desire for countries to reduce their reliance on imported energy sourcesviii.

The part petrol, part electric-powered hybrid vehicles are more and more mainstream. In early 2012, the number of sales of Toyota's hybrid vehicles around the world passed the 4 million markxvi. In 2011, Australians were introduced to the Mitsubishi i MiEV - the nation's first publicly available all electric vehiclexvii. And although not yet available in Australia, BMW's fully electric powered version of the Mini Cooper - Mini E - can manage a range of 240km on a single chargeviii.

An increasing concern over the level of COČ emitted from diesel engines has prompted the production of biofuel alternatives, such as biodiesel: typically made from the oil produced in plant productsxiv. While environmentally sustainable compared to petrol, it typically costs two to three times more to produce the same volumexiv.

The future and beyond

The future of fuels in the automobile industry is vast and varied. Hydrogen, electric, solar and even dung-powered cars are just some of the alternative fuels that are being explored.

With 14 years of research and development in hydrogen fuel cell technology, Hyundai have produced the ix35 Fuel Cell: a zero emissions vehicle that can travel a total of 588km on a single refuelxviii. Recently, American car company, Tesla Motors launched their Supercharger stations in various states in the US: solar carport systems with the capacity to replenishxix. And let's not forget the Dung Beetle - Volkswagen's first methane-powered vehiclexx.

While the fuel of the future is yet to be decided, the Australian government has already introduced initiatives, such as the Green Vehicle Guide, to help motorists make informed decisions when buying vehicles that use less fuel and have lower emissionsxxi. To find out more about what is being done to improve fuel efficiency in vehicles in Australia, visit the Clean Energy Future website.

i Australian Heritage Council, 2003, Linking a Nation: Australia's Transport and Communications 1788 – 1970, Australian Government,

ii Australian Bureau of Statistics, 2012, Motor Vehicle Census,

iii Blackburn, R., 2010, The dummy's guide to fuels,,

iv Encyclopedia Britannica, 2013, Knocking,

v Australian Institute of Petroleum, Lead Replacement Petrol Guide,

vi Caltex Australia, Octane Booster,

vii Exxon Mobil, Ethanol,

viii Serpo, A., 2009, Future fuels: What will power tomorrow's cars?, CNET Australia,

ix Federal Chamber of Automotive Industries, Can my vehicle operate on Ethanol blend petrol?,

x Hagon, T. & Ottley, S., 2011, Ethanol put to the test: E85 v E10 v premium unleaded,,

xi Hagenow, G., Reders,K., Hanns, E.H., Steiger, W., Zigan,D. and Mooser, D., 2010, Fuels, Handbook of Diesel Engines.

xii Ottley, S., 2010, Diesel v petrol: which is the best?,,

xiii Health Effects of Diesel Exhaust, Environmental Protection Agency’s Office of Environmental Health Hazard Assessment & The American Lung Cancer Association of California,

xiv Parliament of Australia, 2010, Alternative Fuels, Australian Government,

xv Caltex, Determining Fuel Prices,

xvi Martin, S., 2012, Cool and green hybrid car sales surge to Australian record,,

xvii Cunningham, W., Fung, D., 2011, Mitsubishi i MiEV, Cnet Australia,

xviii Hyundai Australia, 2013, Hyundai ix35 Fuel Cell Receives Prestigious Innovation Award,

xix Tesla Motors, 2013, Supercharger,

xx Cooper, C., 2010, Poo-Powered Vehicle Hits the Road: No Flies on This Car, CBS News,

xxi Clean Energy Future, 2013, Transport Fuels, Australian Government,