AS WE continue to pay more for our petrol and diesel than anyone else in Europe, car-makers are racing to offer us vehicles using cheaper, alternative fuels.
Volvo reckoned it was the first to sell a manufacturer-made range of cars designed specifically for the purpose with its bi-fuel models.
The cheapest S40 saloon and V40 estate versions will run on either petrol or liquid petroleum gas, and the rest will use petrol, LPG or compressed natural gas. Prices start from £17,000 for the S40 saloon (£850 more for the estate), and come with a full three-year warranty.
This makes them roughly £1,750 more than the standard petrol-only models, but grants of up to 75 per cent of that amount are available from the Government's Energy Saving Trust's Powershift scheme.
Although there is a slight increase in fuel consumption when using LPG, it costs half the price of petrol or diesel, and represents a saving of £700 for motorists covering 15,000 miles a year.
The change between petrol and LPG is pretty straightforward, and involves no more than flicking a switch on the dashboard. The fuel supply then automatically switches from petrol to gas, or from gas to petrol.
As gas - either liquid petroleum or compressed natural - costs roughly half that of petrol or diesel, the obvious question is why would you ever want to use petrol instead.
The answer is that gas is currently available from just 1,000 filling stations throughout the whole of Britain, so you still need to have the back-up of petrol. New gas sites are currently being added at the rate of three a day, and that is due to be increased substantially.
Additionally, an increasing number of companies are installing their own pumps, and then the cost of buying the gas in bulk is halved again. At just 38p per litre it begins to become irresistible for those to whom it is a viable proposition, especially high-mileage users.
In the case of a Volvo V40, for example, the savings over the running costs of a standard 1.8-litre petrol version can be £350 even for private motorists doing just 7,500 miles a year. This is based on the standard car averaging 35mpg on petrol at 82p a litre, which, at 15,000 miles a year results in a fuel bill of £1,600.
By using LPG the cost goes down to just 38p per litre and the economy figure falls slightly to 31mpg, which over 15,000 miles results in a fuel bill of £880 and a saving of £720, or £360 for half the annual mileage.
The figures for compressed natural gas are; fuel at 48p per litre, economy of 35mpg, an annual fuel bill of £935 and a saving over petrol of £660 based on an annual mileage of 15,000.
Of course, there is another alternative, which is to use diesel, because you get many more miles to the gallon. Typically, the Volvo manages about 52mpg on diesel at an average of 84p per litre, which at an annual mileage of 15,000 works out at £1,100, giving a saving over petrol of almost £500.
Although the savings with gas are more dramatic, and can be infinitely more so for companies with their own storage facilities, the diesel savings are not to be sniffed at.
Unfortunately, neither are the fumes, which are still feared to be carcinogenic because they carry microscopic particles of unburned carbon.
In the case of the LPG engine, carbon dioxide emissions are about ten per cent lower than those of the petrol engine, and the natural gas engine is even cleaner at 20 per cent less than petrol.
The gas tank is fitted beneath the boot, and does not encroach on load space, and the only outward sign is a discreet badge on the back. There are two fuel fillers, side by side, within the filler flap, and it is not possible to get them mixed up.
In addition to the long-term cost savings, the extra fuel gives the car a range in excess of 500 miles, and there is no discernible difference in performance.
In every other respect the bi-fuel Volvo is exactly the same as its petrol-only S40 saloon or V40 estate equivalents.
The lower CO2 emissions can reduce company car tax liability and vehicle excise duty rates, and the car will be worth considerably more on the second-hand market.
Whichever way you look at it, cars capable of running on LPG make increasing sense, with considerable savings. The Government is urging us all to use them, and is giving financial incentives to persuade us to do so.
The only problem is that duty on petrol and diesel gives the Government the lion's share of its income, so what will happen if we all switch to LPG?
The Chancellor has pledged not to raise the tax on LPG, so it will be interesting to see just how long that particular promise is kept.
FAST FACTS
Volvo V40 1.8 Bi-Fuel
Price: £17,020
Mechanical: 122bhp, 1783cc 4cyl engine driving front wheels via 5spd gearbox
Max speed: 120mph
0-62mph: 10.5secs
Combined mpg: 41
Insurance group: 10
CO2 emissions: 164g/km
BiK rating: 16%
Warranty: 3yrs/ 60,000 miles; 8yrs anti-rust; 3yrs paint