Yup, gotta love the LPG haters and those who can't crunch numbers. They're they ones who miss out on the huge savings LPG has to offer!
With an SVI system, you pay $4000-$5000 to get it installed, get your $2000 rebate (and an extra $1000 if you live in WA) and you will only use slightly more gas than you would petrol (approx. 10-15% more). With LPG prices hanging around the 65c mark and the absolute cheapest petrol being around $1.33, the savings come fast.
The LPG excise will be applied from 2011 onwards. In 2011, the excise will start at 2.5cpl, increasing by 2.5cpl yearly until the capped 12.5cpl is reached in 2015, so there is still plenty of time to save, and I can't see petrol prices dropping either.
FWIW, it would take the average motorist (20,000km per annum) well under two years to recoup the cost of an SVI conversion minus the rebate, even when petrol usage and servicing costs are factored in.
Regards,
Dave