Are you fed up with high petrol prices? I know I am. I own a family SUV and it gets 29mpg on a run but as low as 20 in town. It's low because it has to be an Automatic due to my partially disabled wife driving it.
Now I have just had our car converted to LPG and currently (before Darling messes it up) LPG is half the price of petrol (and diesel). After conversion it gets about 85% of the mileage but on 50% of the cost so you save plenty. The more you drive the faster it pays you back. For me two years (all being equal). Cost £1600 from Essexlpg.net but you will have a local converter nearby.
You lose your car for a week while it's being done and you lose the spare wheel space for a tank. Set against the gains it's a no brainer, just carry some cans of tyre puncture repair and inflator (go to Halfords) or have (as us bikers know about it) Slime put in your tyres.
You get in and the car starts on petrol then after a short while it switches over to gas. It's just as well that a led tells you on the dash as I wouldn't know otherwise. I guess the minimal power loss would be a problem for a sports car but for a heavy bus like my SUV - no problem. I'm middle aged and don't drive like my hairs on fire!
I found refuelling a bit fiddly but easy enough just follow the instructions on the pump. Locally on my commute to work I pass 4 stations with LPG and oddly enough the prices vary by 7p a litre. Weird! Old habits die hard and I used the cheapo one. I estimate I'll use no more than £5 of petrol a month for my monthly 1000 miles. Bet you wish you could say the same eh?
When you've converted don't forget to tell the DVLA and you insurance company. Send them a photocopy of the invoice and the LPGA certificate. They may want originals I'm waiting to see. Oh and on LPG you get a cleaner exhaust with less CO2 etc. Sweeeet!
If you choose not to use LPG I advise you to join petrolprices.com to get the keenest prices locally. Other tips are get an Adsa Credit card and enjoy 2p a litre off every litre from them. Only use Tesco petrol when they are doing the 5p a litre (when spend £50 in store) offer. Keep your tyres up to recommended pressure, turn off the A/c when you don't need it. Practice smoother driving no traffic light grand prix. Change to a higher gear sooner. Try 60-65mph instead of 70-80 and keep the vehicle clutter free. Take out the junk - less weight = more mpg. Using this I got my own 1.8 people mpv to return well over 41mpg (instead of 35). Leave yourself ten more minutes leeway so you don't have to rush. And the biggest incentive to economise (not the green stuff) is the less you spend on fuel the less tax greedo broon gets from you.
Hope you find this useful.