I have been running on LPG for 18 years now, and have owned many cars with LPG fitted.
I am a car enthuisiest and usually own 4 or 5 cars at any one time.
At the moment I have 5 cars, 3 on duel fuel, 2 without, the cars with duel fuel are registered and used often, the petrol ones only on special occasions.
With the Govt rebate of $1250, it shouldn't cost you more than $1000 to have your vehicle fitted with LPG, if anyone quotes more than $2250, look elsewhere, my last one was a difficult, specialized fit, and only cost $2300.
Youwould preferably have the gas mounted under the deck, which requires a shroud, this may cost a little extra.
The cost of the conversion would be saved in your 1st 90 days if your doing a lot of kms, loss of power is small or even non existant, but there are a few things to watch out for when fitting.
You don't say if its a 4 or 6 cylinder, I wouldnt hesitate if its a 6, but give it more consideration if a 4.
Is it carburator or EFI? although carby models work well with LPG, the gas dries out the seals and tends to block the jets, making it harder to run on petrol over time, EFI is a far better system to run LPG.But both systems need to run petrol for an hour or so every week to keep them working.
My 4 litre 6 cyl gives me 420km on 60 litres of LPG, or @73.5 c a litre yesterday,$4410. 68litres of petrol @ $1.39 takes me 580 km, = $94.52.. I'll let you do the math.
Fitting LPG will not make your car more valuable when you come to sell, just more interesting to buyers, I never fail to sell an LPG car quickly, but never get any more than I would if it wasn't fitted with LPG.
How long will you keep the car? I never fit LPG to a car I don't plan on keeping for at least 18 months, I just sell it off a bit earlier.
Shop around, ask people with LPG cars, the best fitters in your neighbourhood, when you find the right company to fit it, ask questions, where will the tank go? where will they fit the fuel guage in the dash? I prefer my guage on the console, but fitters like to put them on the dash.warranty and servicing?
The first car I bought fitted with LPG, I really didn't want, but it was the only car in my price range, after 2 weeks I swore I would never own another car without LPG, I still feel the same way.