Rising petrol prices and better technology have triggered an "educated rush" in Brisbane to switch cars to gas fuel with experts now predicting the number of gas-powered cars will double over the next decade.
The pressure on US oil caused by 2005 Cyclone Katrina renewed interest in LPG (autogas) as an alternative fuel, which was ignited again by the Federal Government's decision in 2006 to introduce a $2000 rebate.
Now, rising oil prices have pushed LPG (autogas) back into the spotlight.
LPG Australia predicts the 650,000 cars that have switched to gas - or have been bought to run on gas - will jump to 1.5 million over the next 10 years.
Brisbane-based LPG conversion firm, Carb and Gas in Woolloongabba, says rising oil prices are the latest catalyst to a burgeoning replacement fuel industry.
Owner Scott Hasted said smart thinking was the biggest change behind Queenslanders' decisions to switch from petrol to LPG (autogas).
"What has changed, to put it in blunt terms, is the average IQ of the person fitting their car to gas has gone up dramatically," Mr Hasted said.
"Environment, dollars and cents - and the fact that LPG has been regarded as a taxi fuel forever. What has happened in a very short space of time is the technology of the systems has leapfrogged incredibly."
Autogas produces 90 percent of the carbon dioxide of traditional petrol, making it a 10 per cent cleaner fuel source. A conversion costs between $3000 and $4500 depending on the engine type.
But Mr Hasted said new fuel injection technology now gave gas-powered vehicles similar performance to petrol-powered engines.
"Now you convert it, you drive it, you can't tell the difference between each fuel, so the technology is absolutely proven," he said.
"In the last two years on a bad week we might do one or two conversions," he said.
"And at the moment we'do 30 conversions a week, if we could," Mr Hasted said.
"But we can't physically do it."
Mr Hasted says his firm has 65 cars waiting to be converted from petrol to LPG (or autogas) because petrol prices were so high.
"If you include fleet vehicles, we have in excess of 100 jobs booked in."
Queensland has 9.1 per cent of Australia's gas-powered vehicles, with most in Victoria (44 per cent), New South Wales (20 per cent), South Australia (14 per cent) and Western Australia (11 per cent), followed by Tasmania (0.8 per cent) and the Northern Territory (0.22 per cent).
LPG Australia chief executive officer Steve Woodward agreed that new technology and rising fuel prices were the critical factors for people to convert to autogas.
"Since the Federal Governnment rebate started, we have gone from 50,000 conversions a year to 125,000," Mr Woodward said, based on figures to June 2007.
He said only racing drivers would notice the difference in performance.
"If you're going to race two cars down the main straight at Bathurst, you will notice the difference," he said.
"But if you are going to be doing normal driving, nowadays you are not going to notice the difference."
Just over 650,000 vehicles have "switched" from petrol to autogas since August 2006, representing about 5.5 per cent of Australia's vehicle fleet.
"We expect that figure to more than double to around 1.5 million cars by 2018 if the price relativity stays around where it is today," he said.
Mr Woodward said the conversion rate "per capita" showed how much growth was possible in Queensland.
In South Australia, 4.8 people per thousand switch across to autogas, with Victoria at 4.7 per thousand.
"In Queensland, it is 1.2 conversions per thousand and in New South Wales it is 1.5 conversions per thousand," he said.
"Now, there is no really good reason why the conversion rate to LPG should be four times in South Australia, than it is in Queensland and New South Wales."
Ford Australia - one of three major car makers who build cars with their own factory-fitted gas systems - said 13 per cent of their sedans in 2007 were gas-powered.
That proportion jumps to 41 per cent for their station wagons and to 37 per cent for their utes.