If you can afford to run a Rolls-Royce you don't worry about the petrol costs. That is true. It is also true that it is easier to save money than to make it so when the chance arises to run a Rolls-Royce at half price why not make the best of the opportunity. I do about 20,000 miles a year so if Liquid Petroleum Gas at half the price of petrol is an alternative then there is a worthwhile saving. I made enquiries with the Rolls-Royce Specialist who always services my car and was told that the Silver Shadow II will give 13 miles per gallon on gas instead of 15 on petrol, that all motorway service stations sell LPG and that the cost of the conversion would be £2,200 including upholstering the boot where the gas tank would be fitted. On the strength of those three facts I ordered the job to go ahead because it appeared that the conversion would pay for itself in one year.

We left the car with the Specialist whilst we went to New Zealand for four weeks over Christmas. The work was not finished when we returned but it was done a week later. The first impressions were disappointing. Performance on gas was pathetic and on cruise control, which I use all the time on the motorway, it would slow down on hills. That didn't last long because the gas soon ran out and there was no more available. I wasted a lot of time going in to every motorway station looking for gas but they didn't have it, nor did anyone know where I could get it. On the M4 it is available at two stations going east but none coming west because the pumps at Reading west never work. I did find a tank at Raglan but he is only open between 7.30 in the morning and about six in the evening. When I go to London I pass through Raglan at 5.30 am and get back about 10 at night.

The salesman came to see me from Midshires Farmers from whom I buy mains gas for my offices. He could offer me a tank at home if I agreed to use at least 10,000 litres a year. My calculation was that I would use 7,500 litres but that included filling up at the remote end of the journey. We settled on an encoded key so that I can draw gas 24 hours a day from tanks at Countrywide stores in the area from Brecon to Evesham. The magic key tells a meter to invoice me at the end of the month. So far I have not used this facility because the tanks are not yet installed.

The car went back to the Specialist for tweaking. The cost of the conversion had been £3,258.77 which was a thousand pounds more than I had expected but at least the boot was very well trimmed and the carpet had new leather binding in the original colours. It was now down to the size of a Spirit's boot. The rear springs had been adjusted to compensate for the weight of the gas tank and that made the springs creak, groan and bang continuously especially when I had a customer as a passenger who had never ridden in a Rolls-Royce before and wondered what was so great about these cars. The tank was somehow adjusted so that it held more gas. It now holds 80 litres and gives a range of 180 miles. There is a fuel gauge which reads L for low when full and the same when empty so it is useless. The only way to guess how much gas is in the tank is to look at the trip meter and this only works if you have remembered to zero it when re-filling.

Filling up with gas takes a long time. It is about three times as slow as pouring in petrol. Your finger gets tired pressing on a spring loaded button and the storage tank is not under cover like a petrol tank but away across the yard in the open.
The Shadow II has carburettors so it will not start cold on gas. That means the best procedure is to switch off from gas and go to petrol before stopping if the car is to be left for more than a couple of hours. The switch over can be done whilst moving. You press a button on the useless fuel gauge so that is shows C for change. This cuts off the petrol and leaves you running on what's left in the carburettors. It will take you about half a mile. When the petrol runs out you can feel the loss of power so you press the button again and the C changes to L and gas flows and the engine picks up. There is, however, a danger in the procedure. I did it one evening coming through the village before pulling into my driveway to garage the car for the night. I pressed the button to C and expected to be halfway up the village before it conked out but I had estimated wrongly. When changing from gas to petrol it doesn't take half a mile, it happens almost immediately and I stalled on a sharp corner, lost the power steering, had to wrench the wheel hard around, prayed that the accumulators would still operate the brakes and managed to come to a stop without crashing. Then it was back into Park and start on petrol. Panics like that are not what I want in a Rolls-Royce.

From the expenditure on fuel, even when I found gas, I began to suspect that there was no saving compared to using petrol continuously. Certainly I was wasting time searching for gas. The mileage was checked on three occasions and an mpg on gas of between 9.8 and 10.2 was recorded. That was well below the 13 mpg that had been promised.

An accurate test was then conducted. Laila drove the car to Nelson Service Station near Hereford, 27.65 miles away, and filled both tanks. She came home on petrol and then went back to Nelson on gas so the same distance was done on the same day, at the same temperature, on the same roads with the same driver without traffic jams or high speeds and with a warm engine in both directions. It was average driving on an average day. She filled up again using the same pumps and put in 11.65 litres of gas and 7.97 litres of petrol. Thus she had done 10.79 mpg on gas and 15.77 mpg on petrol. The gas that day cost 39 pence a litre and the petrol was 76.6 pence so the journeys of 27.65 miles had cost £4.54 on gas and £6.11 on petrol. There was a saving of £1.57 or 5.678 pence a mile. At that rate the conversion to gas would pay for itself in 57,392 miles.

The three facts I was given in the first place were wrong but I don't blame my Specialist because this was the first gas conversion he has done and he has probably lost more on it than I have and for sure he wanted the conversion to succeed because if Rolls-Royces become cheaper to run then maybe he well sell more of them. That leaves two further factors: that LPG does not spoil the environment and that I have an alternative fuel if petrol is not available. I could not care less about the environment. I cycle more than I drive and have never ridden a bicycle to help the environment; I just love cycling. I don't particularly like driving, especially on modern, crowded roads, so if I have to drive I want a good car and only the Rolls-Royce satisfies me - on petrol, not gas. The alternative fuel factor carries no weight because I would welcome any excuse to not travel. I can earn a living with a phone, fax and e-mail so being stranded with a bicycle in the Brecon Beacons when there are no cars on the road is luxury, not hardship.

So where do I go from here? The car has done 120,000 miles. I bought it at 30,000 and had the Harvey Bailey suspension and stainless steel exhaust fitted so it handles perfectly and manages 120 miles an hour easily. Acceleration is about 8 seconds to sixty which is a tribute to the exhaust system. The performance on gas is quite different. If I wanted something big, cheaper and faster I would get a diesel powered Transit van; the white ones seem especially fast. The LPG has destroyed all the charm and delight of the Rolls-Royce. It has to be removed. In the next twelve months the car will be re-painted and some woodwork and leather improved to bring the car back to as-new. That is when the LPG can be taken out and the boot restored to its spacious glory. Whatever the cost saving of gas, it so damages the car's performance that I would rather not have a Rolls-Royce than have one on gas. Meanwhile, I shall save my 5.6 pence a mile whenever I can

Postcript.

The whole system was removed 5 years ago when Shadow was re-painted, a £60,000 splash about which I have never had the courage to write. The end result, however, was good. Didn't Royce say you remember the quality long after you have forgotten the price?