Elgas LPG Gas Blog

7 LPG Gas Conversion Myths - LPG Cars & LPG Vehicles

There are a number of LPG car conversion fallacies that persist because of a lack of information. 

To help clear the air, I’d like to share some facts with you so you can make your own evaluation.

LPG Cars - 7 Common LPG Car Conversion Misconceptions:

Camry Hybrid1. LPG cars no longer save you money

2. Loss of performance

3. Voids your warranty

4. LPG is less safe than petrol

5. Loss of boot space

6. LPG is hard to find

7. LPG cars are hard to fill  (See Video)

LPG Cars – LPG Vehicles

LPG cars and other LPG vehicles are cars and vehicles that are fueled by LPG – also known as "autogas".

The other LPG vehicles are typically light commercial trucks, utes (pick-up trucks) and tradesperson vans.

LPG cars have internal combustion engines and are frequently dual fuel – running on either LPG or petrol (gasoline).

Dual fuel cars have two fuel tanks, with one for LPG and one for petrol, selectable by the driver.

Some LPG cars are LPG only but the engine is essentially a gasoline engine.

LPG Car Conversion

What is an LPG car conversion?

You start with a car powered by a petrol fuelled internal combustion engine.

An additional fuel tank and filler connection must be added to the car for the LPG.

The tank can be a round toroidal tank that fits in the spare tyre well or a cylinder that goes in either the boot (trunk) or under the car, if there is sufficient room and clearance.

The fuel intake manifold system must be modified to allow for the delivery of an LPG – air mixture to the combustion chambers.

There are four types of LPG car conversion systems, including:

1. Converter-and-mixer systems

2. Vapour phase injection (VPI)

3. Liquid phase injection (LPI)

4. Liquid phase direct injection (LPDI)

A manual fuel selector switch and gauge is added inside the car.

LPG Conversion - LPG vs Petrol Car

An LPG conversion is when a petrol - gasoline - powered car, ith an internal combustion engine, is converted to run on LPG.

The LPG can be propane, butane or a mixture of the two.

• LPG conversion cars have lower running costs.

LPG may actually prolong engine life.

• Autogas (LPG) is less expensive than petrol or diesel.

Engine oil and spark plugs need changing less often with LPG, so service costs are reduced.

• Environmental benefits include reduced particulate, CO2 and NOx emissions,

• Octane ratings over 100 allows for higher compression ratios, which can increase power output.

• The biggest negative is the extra cost involved in converting a car to LPG.  However, the cost is typically recovered quickly through the realised savings.

• In some countries it may be a bit more difficult to find an LPG service station but, in most countries, they are becoming more numerous every year.

When comparing an LPG vs petrol car, regarding the cost of fuel, LPG is about half the price of petrol but your car will use about 20% more LPG that petrol.

The result is that you still save about 40% on your fuel costs.

This savings will more than cover the cost of the LPG conversion, if you are a driver that racks up a high kilometre count.

Where Do the Myths Come From?

Sometimes tall tales get told so many times that people start accepting them as facts. 

The problem can also come from very out-of-date information that may have, at one time, been factual but is no longer true. 

This is the case with the myths surrounding LPG conversions and autogas.


LPG Conversion Cost - LPG Still Saves You Money

Fuel consumption for LPG is greater than petrol but it is more than offset by a much lower price. 

The reason for the difference in consumption is the difference in energy content. 

For example, unleaded E10 has 31.2Mj/L while Autogas has 26.8Mj/L. 

This equates to only about a 14% difference.

Some people make wild claims regarding the comparative fuel consumption of LPG versus petrol powered vehicles. 

The only way to compare accurately is using the identical make, model, year, engine and transmission, with the only difference being the fuel. 

This removes all of the other variables including the human factor, like a light or heavy foot.

We can do this using the info from the Green Vehicle Guide government website.  

Selecting the Ford Falcon Petrol vs Ford Falcon LPG, we can compare fuel consumption data for identical vehicles. 

This fuel consumption data is available for all vehicles sold in Australia. 

The numbers in these otherwise duplicate vehicles are 9.9L/100km for Petrol and 12.3L/100km for LPG. 

So, petrol consumption is only about 20% less in comparison to LPG.

LPG versus Petrol Consumption

LPG Conversion MPG or KM/L

This means breakeven is when the price of LPG is 20% less than petrol. 

For example, if petrol is $1.50, breakeven for LPG is $1.20. 

However, LPG pricing is much lower than that, currently at around $0.75 in Sydney, so about 50% less.

Try inputting your own numbers in this autogas savings calculator:

How Much to Convert Car to LPG

The cost of conversion is dependent upon which type of equipment you choose.

There are four types of LPG conversion systems:

1. Converter-and-mixer systems

2. Vapour phase injection (VPI)

3. Liquid phase injection (LPI)

4. Liquid phase direct injection (LPDI)

Conversion prices can range from around $2,500 to over $4,000 for LPDI models.

No Loss of Performance with LPG Car Conversion

no loss of performanceMany years ago, when LPG conversions were in their infancy, the loss of performance issue had some basis in fact. However, it is no longer true.

A vehicle with a state-of-the-art liquid LPG system produces at least the same amount of power when running on LPG, as compared with running on petrol.

Liquid injection LPG systems are the latest generation in automotive LPG fuel system technology

You get a substantial fuel savings with LPG Autogas, combined with equal engine performance, impeccable drive-ability and lower tailpipe emissions.

LPG Car Conversions Do Not Void Your Warranty

LPG conversionYour new car warranty remains intact unless the LPG conversion directly causes the problem. 

Given the long track record of LPG conversions and ever improving technology, it would be rare that the conversion would ever cause a problem that would affect your warranty.

LPG may actually prolong engine life.

LPG systems are so reliable that more than 1 million LPG systems have been factory fitted by automobile manufacturers around the world. 

Ford chose a Liquid Phase Injection system for their factory equipped LPG Falcon EcoLPi. 

Holden elected to go with a Sequential Vapour Gas Injection System for the LPG Ecoline Commodore. 

Both come with full factory warranties. 

The same liquid and vapour technologies are also available for aftermarket conversions.

The manufacturers of conversion systems (some call them kits) are so confident that they offer extended warranties on their LPG systems. 

For example, Orbital Autogas Systems offers a 3 year / 150,000 km warranty, depending on the model.  Sprint Gas offers a 3 years / 100,000km warranty on late model vehicles.

LPG is Just as Safe as Petrol

Autogas is safeLPG has been used safely in Australian vehicles for decades. 

Australian LPG fuel systems must meet the strict requirements of the Australian Standard AS1425, which covers specifications, installation and maintenance.

LPG systems are fitted with a myriad of safety devices and design considerations. 

Pressure relief valves, automatic shut-off systems, back check valves, and heavy gauge steel tanks are amongst the safety features employed.

The litmus test for safety is the cost of insurance. 

It costs no more to insure an LPG car than a petrol car. 

If LPG cars were more dangerous, you can bet the insurance companies would be charging more to insure them.

No Big Tank in the Boot

Toroidal LPG tank in spar tyre well.The days of the LPG tank taking over your boot are gone. 

There are new tank innovations that preserve your boot space for important things, like golf clubs and luggage!

The new toroidal LPG tanks are doughnut shaped and typically are fitted within the spare wheel well. 

They come in various sizes to fit just about any car, ute or SUV. 

They are also available in versions suitable for either liquid or vapour injection systems.   

Toroidal tanks come in both interior and exterior mounted styles. 

The spare is typically replaced by a small emergency inflation kit.

LPG Autogas is Easy to Find

Autogas being hard to find may be the biggest myth of all. 

There are over 3,000 Autogas outlets in Australia.  In fact, we have one of the most extensive autogas distribution networks in the world.

LPG Cars Are Easy to Fill

While the nozzle and procedure for filling an autogas tank are different, it is not difficult.  Virtually anyone can do it. 

Here is a ‘how to’ video to show you how easy it is:

Video courtesy of CarAdvice

View more Autogas related blogs

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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.