Converting your car to LPG

Worried about rising fuel prices? Switching to LPG may be a way out - especially with the new rebate
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  • Updated:15 Sep 2006

01 .Converting your car to LPG

Car with hood up

Currently, there are about 500,000 vehicles (including taxis) on our roads that run with liquefied petroleum gas (LPG) — that’s about 5% of all cars. And the rising petrol prices combined with the new Government rebate are likely to make more people think about converting.

LPG costs less than half as much as unleaded petrol. Whether that’s enough to recover the conversion costs in an acceptable time depends on your individual situation - do your own calculation.

Please note: this information was current as of September 2006 but is still a useful guide today.

Pros and cons of converting


LPG is better for the environment. Compared to unleaded petrol, it creates about:

  • 15-20% less greenhouse gases.
  • 30-40% less volatile organic compounds and oxides of nitrogen.
  • 50-60% less carbon monoxide.
  • 80% less toxic air pollutants such as benzene and sulphur oxides. 


 There are disadvantages and inconveniences you should consider before converting your car:

  • In passenger cars, the additional LPG tank takes up space in your car’s boot. In 4WDs, the tank is usually installed under the car.
  • On older cars, there may be a slight loss of power, mainly under heavy loads such as when towing or driving uphill.
  • You should be able to travel around Australia and find LPG refill stations in most places, though you might have to search a little more — there are about 3200 LPG stations, compared to more than 8000 petrol stations. Check their locations on If you convert to dual-fuel mode, you can of course always use petrol if you can’t find an LPG outlet.
  • It may be more difficult to find a garage that can service your car.

More information

For more information on LPG, see the LPG Australia and LPG Autogas websites.


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Liquefied petroleum gas (LPG) is extracted from natural gas or derived as a by-product of the petroleum refining process. It actually describes a whole group of products consisting of one or a mixture of the hydrocarbons propane, propylene, butane and butylene.

In Australia, two grades of LPG are commonly used. The two types aren’t interchangeable:

  • The LPG you use for your BBQ or other appliances is propane only.
  • Car LPG is a blend of mainly propane and butane.

It’s stored under pressure as a liquid. When the pressure is reduced (for example, for combustion), the liquid turns into gas and expands to about 270 times the liquid volume. This means LPG is very convenient to transport and store.

The gas is heavier than air and very explosive. LPG therefore contains a strong odorant (‘rotting cabbage’), so you’re quickly aware of any leaks. If there is a leak, you must immediately remove any potential ignition sources: switch off any electric appliances and motors, extinguish all open flames and ensure good ventilation.

All the components as well as the installation, repair and maintenance of LPG systems are covered by mandatory standards and other regulations.

For example, in all states and territories only a business that meets special licensing requirements is permitted to install, repair or adjust a car LPG system. Search for a licensed installer near you.

  • Before you convert your car, contact your vehicle’s manufacturer to find out whether it’s suitable, and whether the conversion will affect the car’s warranty.
  • Your transport authority has information on particular requirements in your state or territory. It can also give you details of licensed installers in your area. You must inform them once your car has been converted.
  • While it’s unlikely you’ll pay a different insurance premium for a converted car, you should contact your insurer to make sure. In any case, you must inform them once your car has been converted.

The conversion usually consists of the following main components:

  • Tank: while you can convert your car to run on LPG only, the LPG system is usually installed in addition to the fuel system (dual-fuel mode), greatly increasing your car’s range. LPG tanks are considered to be as safe if not safer than petrol tanks in an accident.
  • Fuel lock valve: prevents the flow of gas when the engine stops.
  • Vaporizer regulator (converter): regulates the outlet gas pressure according to engine demands.
  • Air/gas mixer: mixes LPG vapour with air for combustion.
  • LPG control processor: operates in conjunction with the car’s on-board computer to accurately meter the amount of gas for increased economy.

A dual-fuel conversion must ensure that all emission control, engine control and engine management systems and devices remain operational. You’ll have to use the fuel system every now and then to keep it functional and safe — recommendations range from 10% to 30% of the time.

04.Does it pay for itself?


Government rebate

To encourage the uptake of LPG as an alternative fuel, the Government’s LPG Vehicle Scheme offers rebates for the conversion of a petrol or diesel car to LPG, and for the purchase of a factory-fitted LPG vehicle:

  • The scheme will run for eight years.
  • It offers $2000 for the conversion of a new or used vehicle, and $1000 towards the purchase price of a factory-fitted LPG car.
  • The full grant is available regardless of the actual conversion cost, which depends on, for example, the car model and tank size, and can vary from about $2000 - $4000. You may be able to find a cheaper quote, especially if you install a second-hand LPG unit, which is also covered by the scheme.
  • There’s a number of conditions:
    • The vehicle must be registered for private use.
    • The scheme only applies to passenger and light commercial vehicles of up to 3.5 tonnes.
    • The vehicle must be registered in your name and state of residence.
    • The vehicle must be privately owned, not financed through a novated lease or a salary sacrifice arrangement.
    • You can get one grant every three years.
    • The grant applies to conversions or purchases made on or after 14 August 2006. Applications have to be made within 12 months of the invoice date, and can be launched from 1 October 2006.
    • You have to nominate a bank account for payment of the grant.
  • For more information on the scheme and an application form, go to the AusIndustry website, or call the hotline on 132 846.
  • For more information on LPG (for example, to find the nearest installer or station), check the LPG Australia website.

How long does it take?

LPG costs about half as much as unleaded petrol. However, it doesn’t contain as much energy as petrol — you’ll need about 20% more LPG to drive the same distance.

The payback time depends on the number of kilometres you drive each year, your car’s fuel consumption, the cost of the conversion and the price difference between petrol and LPG.

Make sure you assess your situation before you convert to LPG — it may take longer to pay for itself than you want to keep the car for. For example:

  • You drive your family car for 20,000 km a year — mainly in city traffic, where it uses about 12.5 L/100 km of petrol. On average, you pay $1.40 a litre for petrol, and 78 cents a litre for LPG. Your petrol costs are $3500 per year. The same distance travelled with LPG costs $2340 (at 15 L/100 km) — a saving of $1160. Say the conversion costs $3000, it will pay for itself after a bit over two years without the government rebate, or in about eight months with the rebate.
  • The same calculation for a small car using 8 L/100 km of petrol (and 9.6 L/100 km of LPG), travelling 10,000 km per year and being converted for $1600: the savings are $371 per year, and it’ll take about 4.5 years to recover the conversion costs without the government rebate. However, with the rebate you'll have $400 in your pocket from the start.

05.Do your own calculations


What you'll need:

  • The average distance (in km) you travel in your car per year. The Australian average is about 15,000 km/year.
  • The current prices (in $) for petrol/diesel and LPG in your area. If you're not sure, $1.40-$1.50 for petrol/diesel and $0.78 for LPG should give you a reasonable estimate for many areas.
  • Your car’s fuel consumption (in L/100 km). As a guide, a large family car uses around 12 L/100km, a medium-sized car around 10 L/100km, and a small car about 8 L/100km.
  • A quote (in $) for the conversion of your car. This typically ranges from $2000 to $4000, and $2500 is a good average price to use if you don't have a quote yet.
  • To find out whether you're eligible for the government rebate.

LPG conversion calculator