LPG cars

While petrol prices continue to fluctuate, it does seem that the days of 80-something cents per litre are now probably a memory.

While diesel is seen by many people as a more cost efficient alternative, the cheapest fuel continues to be Liquified Petroleum Gas - LPG.

At 40-60 cents per litre, depending upon where you fill up, the attractions are seemingly obvious. Taxi drivers certainly reckon LPG is the way to go.

Holden has a dual fuel VZ Commodore. Ford has just launched a dedicated E-Gas BF Falcon. Expect to see more LPG models in the next 12 months.

Why is LPG so cheap?

Production costs are minimal. LPG is a by-product of the oil refining process; the refineries themselves use it as a fuel source; it's basically the excess supply which is sold.

More importantly, LPG is not subject to the same 38.14 cents per litre excise levied on petrol and diesel by the Federal Government.

However, LPG's tax free status is about to change. In 2011, the government will introduce a tax regime for all fuels based on their energy content.

If you want to interpret this in a generous manner, you could say it is being done to properly reflect the environmental friendliness and energy benefits of different fuels. Or, you could be predictably cynical about it and suggest that it's simply an excuse to gouge more revenue from consumers.

LPG will still end up being cheaper than petrol, but the price differential will be much less than it is now. 

Holden

Holden's dual fuel Commodore Executive is more expensive than the petrol powered equivalent's recommended retail price, which needs to be factored in if you're doing the car purchase/annual distance driven/fuel price sums.

The official fuel consumption numbers (according to the ADR81/01 laboratory test) Holden and Ford are quoting for their gas powered cars reflect the fact that while LPG may be cheaper, you also use more of it.

Holden claims 14.4 litres/100 km on LPG and 11.1 litres/100 km on regular unleaded in the Commodore sedan.

Ford claims 15.5 litres/100 km for its E Gas engine, compared with 10.9 litres/100 km for the upgraded Barra 190 4.0.

The Commodore's 3.6 litre V6 produces 175 kW of power and 320 Nm of torque on both fuels. The system uses petrol on start up, then, if you have flicked the gas switch, automatically transfers to LPG.

The LPG system needs servicing at 15,000km intervals. This involves changing two filters and checking for leaks. 

Ford

Ford's 4.0 litre E-Gas engine in the Falcon is LPG only. It produces significantly less power than the petrol engine - 152 kW compared with 190 kW - and marginally less torque (374 Nm vs 383 Nm.) It's available with the four speed automatic in the base model XT sedan and wagon. It costs the same to add to the Futura sedan or wagon.

Again, it's worth considering that the petrol powered Falcons are attracting substantial discounts. Some models - but not these LPG cars - are also available with the new six speed auto, which gives the Falcon pretty good economy - less than 9.0 litres/100 km - on the highway.

The Falcon and Commodore LPG engines are both fitted with hardened valve seats, to compensate for the absence of a cushioning/lubricating effect of an atomised petrol/air mixture.

You can also have your current car fitted with a dual fuel LPG kit, though this is not possible with all makes and models.

Kit prices range from about $2500 for a simple single point injection system, to $4000 for a multipoint system.

"There's no great performance disadvantage with an aftermarket dual fuel system as long as you get it properly fitted by a Motor Vehicle Repair Industry Association (MVRIA) licensed installer," the NRMA's Jack Haley says.

"A dedicated gas computer should be part of the system. Some installers cut corners by not including it, which results in the car running too rich, adding to your fuel costs."

However, aftermarket installations will be less efficient than the Ford and Holden factory systems. Expect consumption to rise by about 30 per cent compared with petrol - yet another factor to consider when trying to work out how to drive your precious petrodollar further. 
 
Article by Bill McKinnon, December 2005.