I got a direct injection gas conversion put onto my G6ET 6 weeks ago and so far very happy with it. I'm not sure what the fuel economy is but it only costs me half as much as petrol. It costs me about $23 to fill gas tank (at about 45c per litre) and it gets me about 250ks around town. Heaps more than that on a trip. There is a noticeable difference in power when you drive it hard, but around town you would never know. The drop in power doesn't really phase me cos when I want power I just switch it back to petrol. If you are going to convert your car look into LIQUID INJECTION (just google it), I wish I had known about it before I converted my car to normal direct injection. Its being claimed you actually get more power than petrol!! As far as I understand its because the lpg is injected as a liquid, it converts back to gas as soon as its injected which cools the engine and hence more air into the engine. Ford are actually introducing liquid injection into all their dedicated gas range as of next year. Hope this helps!