after you have done the maths then LPG is definitely an option. I have a 3.0rn automatic and will be doing it this year if all goes well, as i hope to run this car for many years to come. even though i don't use it for commuting and it is primarily a weekend holiday car, the maths works for me as long as the car runs for the next five years and i keep doing big runs. i was quoted 1500 pounds for an all singing dancing factory fit layout OEM system with a tank in the spare wheel well and a centre mounted inlet near the the tow bar.
mounting the gas inlet centrally at the rear of the car means you can fill up from either side more easily.
finally - you will probably know that LPG has much less harmful emissions than diesel and infact in singapore and hong kong all the taxis are required to run on LPG as the issue of smog and car pollution is a major issue there - and i believe london has missed a trick in not considering LPG as a way out of our own smog problem.
