However, as more manufacturers come on board with factory-fitted conversions, the range of vehicles on offer to UK fleets expands.
Vauxhall seems determined to offer a gas option for every vehicle in its range, and the latest offering to get the Dualfuel treatment is the sleek Astra Coupe.
It is true that the LPG conversion is only offered with the least powerful engine in the range, but the 123bhp 1.8 litre unit in the coupe is brisk enough, making it an attractive proposition to user-choosers.
The conversion pumps up the price for the Dualfuel coupe by £1,925 over the standard car, but a grant of 60% towards the conversion cost can be applied for through the TransportEnergy PowerShift programme.
A 52-litre fuel tank ensures about 300 miles of travel on gas before you need to refill, and there is a petrol tank as back-up.
The Astra Coupe comes with sports seats, air conditioning, electric windows and (heated) door mirrors, a CD/radio, remote central locking, ABS, alloy wheels, traction control and sports suspension.
It retains the nimble handling characteristics of the rest of the coupe range and is a truly entertaining drive over your favourite backroads.
Pushing hard along country lanes, the Astra always feels well balanced with limited body roll and positive steering which allows you to pick your desired line around the twistier sections with millimetre precision.
Despite its sporty nature and lowered suspension, the ride is not too harsh on its 16-inch alloy wheels while the brakes have excellent feel and stopping power. I don't think the sports seats do my back any favours, despite the standard lumbar adjustment, but overall the Astra Coupe Dualfuel means that you can be environmentally minded and have fun when you drive. We eagerly await the VX220 Dualfuel!
Model: Astra Coupe 1.8i Dualfuel
Engine (cc): 1,796
Max power (bhp/rpm): 123/5,600
Max torque (lb-ft/rpm): 125/3,800
Max speed (mph): 130
0-60mph (sec): 8.5
Fuel consumption (mpg): 27.5
CO2 emissions (g/km): 166
2002/03 BIK tax band: 14% (including 1% LPG discount)
Tax payable (at 22%): £521 per annum
On sale: Now
Price (OTR): £17,075
Dualfuel Rover choice for serious fuel-savers
MG Rover has gained a reputation for rapid product development with the limited resources available since its independence from BMW.
And now it has turned to LPG conversions of its 1.8 litre K-series engine to boost the environmental credentials of its range and offer an alternative to petrol and diesel. MGs (except the TF) and Rovers using the 120bhp version of the 1.8 engine will be eligible for the conversion which achieves the maximum 60% PowerShift grant to offset the £2,195 additional cost of choosing the LPG conversion.
Although the LPG range is on sale, with MG Rover dealers equipped to carry out the conversions, the company has not yet released performance and fuel consumption figures for running on gas, other than to confirm an approximate 10% increase in fuel consumption and similar loss of torque.
I sampled the 75 Tourer, which seems identical to the standard car with the exception of the LPG badge on the tailgate and the extra fuel filler cap. Inside, the sumptuous interior of the 75 remains, with the addition of a switch on the centre console to select either gas or petrol. An LED gauge above the switch indicates the level of gas, with the other fuel gauge showing the level of petrol remaining.
The interior of the Rover 75 is undoubtedly the classiest available for the price. The polished wood, two-tone light colours contrasting with black console and dark seats, and bespoke instruments and switches, make the 75's cabin a special place to be. The Tourer is easily as elegant as the saloon and offers the advantage of improved versatility and carrying capacity. However, with just 115bhp on tap, the engine sometimes feels laboured in picking up speed.
Unfortunately, this is the only engine currently offered with the gas conversion, and if performance is a priority then you will be disappointed.
However, the engine is refined and rarely makes itself heard, while the Tourer handles itself with decorum, exploiting the chassis.
But when the 75 2.0CDT (with a supremely smooth common rail diesel) is equally refined and offers more torque, you have to be really committed to cutting down on fuel costs to pick the LPG Rover.
Model: 75 Tourer 1.8LPG Club SE
Engine (cc): 1,795
Max power (bhp/rpm): 120/5,500
Max torque (lb-ft/rpm): 118/4,000
Max speed (mph): 117
0-60mph (sec): 11.4
Fuel consumption (mpg): n/a
CO2 emissions (g/km): n/a
On sale: Now
Price (OTR): £21,305
* LPG fuel consumption and emission figures to be confirmed
Subaru trial success puts LPG on agenda
SUBARU will introduce a factory LPG conversion for its cars in 2003 after successful trials with a Legacy prototype.
The car, which is still undergoing final approval, should be available in showrooms next year and will lead to an LPG conversion for the 2.0 litre and 2.5 litre four cylinder engines as well as the 3.0 litre flat-six.
It means that gas conversions should be available over time for the Impreza and Forester models, as well as the Legacy.
In an effort to ensure the traditional Subaru handling traits are not compromised, it will use a carbon-fibre gas tank, saving 20kg in weight over a conventional tank.
Subaru business sales and used cars manager Harvey France told Fleet NewsNet: 'In a way this is our equivalent of diesel. We are delighted that we will be able to offer a full factory-approved conversion and this will help fleet operators improve their fuel costs.'
A diesel-engined Subaru is several years away from production, although the company has been developing a 'boxer' diesel engine (one with horizontally opposed cylinders creating a lower centre of gravity) in the laboratory.
The gas tank on the Legacy prototype can hold 70 litres of LPG offering a range of 300 miles on gas, and also uses a 62-litre petrol tank.
Middle East problems could make LPG the fuel of the future
RISING fuel prices as a result of tension in the Middle East are expected to raise the profile of liquefied petroleum gas (LPG) as a lower-price alternative to petrol and diesel.
Traditional fuel prices currently average 75p per litre (£3.41 per gallon). By contrast, LPG retails at about 36p per litre (£1.64 per gallon).
LPG provider Calor Autogas believes that the price differential will persuade more fleets to take alternative fuels seriously.
Miles Lant, managing director of Zone One consultants, who works with Calor Autogas on its LPG-diesel programme, said with more manufacturers coming of board with factory gas conversions and a gradually improving refuelling infrastructure, the onus was now on car buyers to take advantage of fuel cost savings.
He told Fleet NewsNet: 'If fuel prices go up over the next few weeks people will begin to notice, and even if the price of LPG rises there will still be a significant difference between it and conventional fuels.'
Lant claimed the arguments were stacking up in favour of LPG, with wider availability of refuelling points, while the cleanest LPG engines receive a 100% discount on congestion charges being introduced in London next year.
'If a fleet is interested in gas-powered vehicles and there are no sites in its local area, CalorAutogas can install a tank on site so gas is readily available,' he said.
He said the motor trade had begun to change its attitude to gas-powered vehicles, with improved residual values closer to petrol equivalents of LPG–converted cars.
He said: 'Four or five years ago if you wanted to lease a gas-converted car, some leasing companies would have asked to have the gas conversion removed at the end of its lease period.
'Now they are happy for the equipment to be left because the cars are not so difficult to sell on the used market.'
Although many fleets had chosen gas cars and vans with the aid of Government grants, Lant said support schemes, such as PowerShift, needed to refocus effort on older vehicles which are likely to cause greater pollution.
He said 'People don't want to pay the cost of a gas conversion when their vehicle is only worth a few hundred pounds, but grants are only available for vehicles up to five years old.'