With fuel costs seeming to rise every month or quicker, the car is becoming an increasingly expensive item — a luxury, some would say. But this does not help the business person who relies on the company car to transport them often long distances around the country.

Public transport is fine, as long as it is between major urban centres, but when it comes to moving in the most effective way between two offices, then the car is unbeatable for convenience.

So how do you make it cheaper? Electric power is still years away to be truly effective for long distance executives. Diesel has become more viable as it is, finally, thanks to increased refining capacity, the same price as petrol.

But there is one option which offers identical performance and avoids the London congestion charge to boot — liquefied petroleum gas (LPG).

In the UK market this is propane and its main advantage is it currently costs about 54p a litre at the time of going to press, compared to petrol/diesel of about 106p/litre.

This is essentially because it is not taxed anywhere near as highly as conventional fuels, so every time you fill up, the saving is tangible.

LPG is not a new technology — in some countries it has been in use since the 1940s, and in the last decade it has become more popular in the UK as fuel prices rise.

About 150,000 vehicles on UK roads now run on LPG and there are more than 1,700 sites where they can be refuelled, 18 of which are in Oxfordshire, including Calor Gas depots such as the one in Osney Mead, Oxford.

Statistics indicate LPG is also far greener, emitting 17 per cent less carbon dioxide than petrol, and far fewer particle emissions than diesel.

All this begs the question why this has not caught on before now.

The main reason is again probably price. A typical LPG conversion costs in the region of £1,600 for a car or light van, which means you would have to drive a long way before any real savings are made.

LPG vehicles also use ten per cent more fuel than their petrol/diesel equivalents and require an extra fuel tank to be fitted (usually in the boot), reducing luggage space.

But a fleet operator where the vehicles are doing 20,000 miles a year should start to see the benefits relatively quickly.

I tested a Vauxhall Insignia 1.8 for a week and effectively there is no difference between it and the petrol model in terms of performance.

The car runs on petrol initially before flipping over to LPG automatically after the engine reaches about 40 degrees centigrade, but the driver does not notice this at all.

On the dashboard there is a separate indicator showing the fuel level and the extra tank is situated under the carpet in the boot where the spare wheel should be.

Instead of the spare, I was issued with a can of tyre repairing foam which, fortunately, I was not required to use.

Refuelling is not quite as straightforward as at a conventional pump. The nozzle has to be lined up and twisted into place and there are in fact two different technologies, depending on the service station used.

But I suppose you would get used to it after a little practice.

Otherwise, there is no noticeable difference between the LPG conversion and the standard car.

The Insignia itself is a fairly typical sales rep car. It’s comfortable enough to cover long distances and handles reasonably well, although the 1.8 engine feels underpowered in such a large hatchback and I don’t think that had anything to do with the LPG.

In fact, it was also fairly economical, although the computer reading for miles per gallon was obviously misleading as it is geared up for petrol. I reckon it was still returning comfortably above 30mpg.

What all this proves is that there is definitely a future for LPG and, if economies of scale can bring the conversion costs down, then it could become even more attractive, especially as the Government has committed to keeping the level of fuel duty at a low level for the next five years.

o LPG converted vehicles are on average 40 per cent cheaper on fuel costs o Many can avoid paying the London congestion charge and may even be eligible for cheaper car parking schemes o In some cases LPG-powered cars are eligible for lower road tax o LPG produces 17 per cent less CO2 than petrol and 120 times less small particulate emissions than diesel Contact: Car supplied by Calor Autogas: 0800 216659 Web: www.lpg-vehicles.co.uk