I have converted several 4 x 4s to LPG, namely a 2001 Range Rover Vogue 4.6, a 3.2 "Vauxhall" Frontera Limited and, most recently, a grey import Harrier (RX300), which I kept for 3 years after conversion. It cost £1200 and was done by a team of Poles in Wales, and, once I got my local LPG expert (Dave Croft in Chesterfield) to sort it out properly, it worked a treat, which is more than I can say for the RR. It made the fuel guage a bit tempremental (in other words, rubbish) but as it was completely automatic in the switchover, it didn't really matter. It was clean, green and improved the mpg in terms of cost, but not in actual fuel use. Doing an average annual milegae of around 10k p.a., I reckoned it had paid for itself in less than 2 years. Having said that, when I traded the Harrier in on a 2004 RX300, I got about £600 more back because of the conversion, which effectively makes the payback time shorter still. I'm still considering whether to convert the RX...... I didn't consider that the servicing costs were worth discussing, as, once Dave had sorted the system properly, it never needed anything else doing to it over the nearly 3 years of use, apart from having to tap the tank occasionally to free off a sticky sender unit......