Hi Nick,
Why LPG? What advantages does it have?
It's cheaper, it's cleaner, and the technology has been in place for over thirty years, i.e. nothing airy-fairy about it.
I don't know of anywhere that sells it.
Hmmm. Now, is that an availability problem or a political problem?
Years ago, I drove for the local newspaper, and their vans ran on propane, and it lasted only about 80 miles, and we then switched over to gasoline (I'm sure there was some compromising goin' on...) for the rest of the night.
Indeed. It sounds like a half-assed and casual application. Every taxi in Australia, without exception, runs on LPG, nearly all of them are LPG only and come that way off the production line. I guess they would get at least 250 miles from a tank round town. The standard tank is about 15 US gallons. The cost of LPG is never more than 40% that of petrol.
We have a lot of LPG and the government made a big push to get it into cars after the Yom Kippur war by keeping the tax down.
Out on the Interstate, where I do a lot of driving, the economy can be quite dramatic. The only things that count are how far you go and how much it costs. You check that and then check how much petrol you could have bought at the adjacent pump, and derive the petrol mileage equivalent.
The nett result in US terms is 51 mpg.
That is driving normally, normal 28psi, a/c on, 70 on the freeway, 60 on the highway, carrying a reasonable amount of cargo, full tanks, and no dangerous petrol saving stunts.
The car is a 1992 Ford Fairlane with 4 litre six cylinder and dual fuel systems. It is the biggest car made in Australia and about the same size as a Crown Victoria but somewhat lighter, a lot more elegant, and a lot more refined. It also comes with a 5 litre V8 but I guess those days are over for me.
(edit)
And one vital thing I forgot...
LPG does not involve agriculture
But I kind of liked it. But I kind of like dairies. I'm kind of a sicko that way 
