In answer to griffin41's guide about the rising cost of lpg and a few paragraphs about my own experience with LPG.
I must agree that it has indeed risen fairly rapidly in the recent years. I am the owner of a 2000 reg' Vauxhall Omega which was converted by the manufacturer from new and I have owned it for 4+ years. I usually only keep a car a maximum of 3 but can't seem to part with the old girl as she costs so little to run. She has done 130k+ miles and I've only had minor issues and that is due to my lapse in servicing.
I maintain her the best I can with my own knowledge but the LPG system is beyond my capabilities so I dug deep into my pockets and coughed up the fairly decent price of £120 for a service. Why didn't I do that before as it was certainly money well spent. I had a slight issue with the system where it would drop revs for only a moment after about 10 minutes of running and there was a definate drop in power when it switched over from petrol. This all stopped after the service and the increase in power and economy was very noticeable without looking for it.
Some people may call me a scrooge but I like to see how much savings LPG has given me over the years, I have kept a record of all fuel costs, both petrol and LPG and for the 46000 or so miles I have covered and the 1800 gallon used I see an overall average equivalent MPG against the cost of petrol to date of currently 62.04mpg...yes, 62mpg for a 2 litre Omega which isn't a small car by any standards. Against the cost of diesel it equates to OVER 70mpg!!. The best figure I have had was just over 95 when I was see-ing how little fuel I could use over an 80 mile trip and the lowest has been 47 when I did the same trip in a rush!! (Stricly legal of course...NOT) Before you say it, yes I am a sad but at these savings who cares.
Anyway and finally, about the rising fuel cost issue. I was paying only 32.4p per litre up until Sept 05 and since then it has risen steadily. Mr Brown stated it would increase in line with Unleaded penny for penny and not at a greater rate. Unfortunately these increases happened but when the price of petrol dipped for a short while in early 06 lpg stayed the same. Then as petrol increased again, so did LPG so I believe the garages saw fit to keep a little more profit for themselves instead of reducing it inline with petrol. The recent sharp increase in fuel costs has seen LPG rise substantially and at a much greater percentage but I have still found it available currently at 48.9p per litre which even at a 50% increase in nearly 3 years is still way way below the stupidly high cost of petrol. True, I too only get about 80% of the miles per gallon against using petrol as the LPG must use more which I'm guessing is due to it burning better or something but that would mean I could confidently STILL gain savings even if the price doubled tomorrow as petrol is nigh on £1.20 per litre in my local Tesco's. So to say is it worth it, of course it is and I wish I'd had the nounce to go for it much earlier in my driving life instead of poo-pooing it as inconvenient etc etc. Shopping around for the cheapest is also worthwhile as I travel 20 miles when I can to fill up on 70 litres worth as it's 8p a litre cheaper than my local garage so even pennies mean savings.
The person who wrote the guide moaning that he might only be saving 20p per litre in 2 or 3 years if Mr Brown see's fit to increase LPG substantially wants to get a grip on reality!! I'm 100% sure that the people who HAVE to use petrol would gladly swap their fuel costs against yours as it would still probably mean a saving well in excess of £500 a year at 20p a litre. So even after paying servicing costs - which I recommend - would still be a welcome saving.
Anyone not using LPG should seriously look into it. There are many cars available now and the like's of Vauxhall & Volvo to name just 2 fitted them at the manufacturing stage at no extra cost against the equivalent petrol models but there's also plenty of aftermarket conversions around so you don't need to pay extra to purchase one despite what sellers on this site or others may say. It's also said that gas reduces the wear on the engine which has got to be beneficial in the long run so what are you waiting for????
Actually.......come to think about it....you can continue using petrol & diesel then all us LPG users can reap the benefits for longer as if too many people start using it, it may prompt the PM to increase it more. Yes...LPG is rubbish, inconvenient and doesn't save me a penny!!!