Sorry, RogerL, but if you haven't tried it, how are you qualified to answer the query? I know you're entitled to your opinion, but your generalisations are quite wrong.
I've been using LPG for around 12 years now, on three different Range Rovers, so I feel that I am qualified to answer Alan's questions.
I have never noticed any reduction in MPG figures from gas to petrol, nor have I noticed any reduction in performance. My current RR has the gas tank where the spare used to live. The spare now lives flat on the floor, where the caravan spare used to live, with a false floor above it, where the dogs travel, so no loss of boot space. The caravan wheel now travels in the van.
I agree that the range is shorter with my tank, but as there are now well over 2000 LPG stations in the country, I don't find this a problem. I need to stop every 2 hours or so to relieve both myself and my dogs, so we simply time these stops to coincide with fuel top ups.
The biggest problem I have with running on LPG is what to spend the money on that I save every year!!
A website called "boostlpg" has a calculator which works out your annual savings, based on mpg and fuel cost. Since running LPG, I have saved