WOW, 40.8p per litre !!! Thats MEGA cheap. I've had a few cars converted, not had a ford done though. The tank on modern conversions would normally be fitted into the spare wheel well, meaning the spare would have to live in the boot. I found the cars ran smoother and quiter on LPG. There use to be a difference in power, but as the systems become more up to date, there is very little difference, to the point you wouldn't notice. MPG is slightly less, but at the price you mentioned, its still a no brainer lol. Normal costs of LPG are roughly half the cost of petrol, hence big savings on fuel costs. Only thing to take into acount is the initial cost of instalation,,,,, make sure you plan on keeping the car long enough to re-coup the fitting costs. And always go for the best system you can afford, and be SURE the fitter is supplying a certificate of safety/fitting, as you will need this for insurance purposes. Other than that, If I were to ever wonder back to the petrol world, I would have an LPG system fitted again, without hesiatation.