Steve
There are lots of threads on this subject, and a lot of different opinions.
IMHO running LPG makes the RR run with similar fuel costs to the diesel version. Say the petrol does 15MPG, figure 13MPG when running on LPG (because it is less efficient). With LPG at 50% the cost of petrol you are getting the equivalent (money-wise) of 26MPG, which is somewhere around what the diesel does. That's as prices stand now, if the cost of LPG starts going up relative to petrol/diesel things change!
If you are converting the RR with your own money then you will have to factor that into the equation too - you can buy a lot of fuel for £1500 odd! Then you have insurance hassles if you don't have the proper certificate, and some garages won't work on LPG cars - who can blame them!
Best thing to do if you want LPG is find one that has already been converted, and make sure it was fitted by an approved fitter so you get the certificate if your insurance company asks for it. Also check how long ago they had it converted, lots of people sell them not long after having the vehicle converted because poor conversions can cause problems so they get rid of it quickly! You've got to ask if they spent £1500-odd having it converted only a few months ago, why are they getting rid of it before getting the benefit of the money they spent?!
There are a lot of bad conversions, and a lot of people who do this without knowing what they are doing - speak to Peter C about an LPG conversion and see what he thinks about it!
Personally, as much as I like the V8's I wouldn't go anywhere near LPG, but there are equally people who feel the opposite as well!
Matt.
ok thanks for looking i hope someone can help. ps i,ve been looking at a 1998 4.0 hse
