New Zealand imports all it's fuel, but has it's own gas fields. So LPG is reasonably cheap, and like Australia we get Ford and Holden with factory fitted LPG as an option for just over US$1000 extra. After market conversion is about US$2000 to US$2500, and you need to drive about 300 miles every week for 3 years to recover the cost (I've done the calculations only a few days ago for our '88 B200E 240). That's 1 tank of fuel per week. Apparently you use up to 20% more LPG, factory fitted is about 10% more LPG. It is very popular among taxis, who obviously drives a lot. I was told that LPG is up to 110 ROM (octane) equivalent, but yesterday I saw on a local web site of the LPG supplier that it's 99 RON. Still better than 98 unleaded we get here at selected service stations (normally only 91 and 96) for double the price of LPG! (And the B20 is specified 100 RON minimum by Volvo.) One major advantage is that your oil and plugs stay clean. On LPG you don't change them because they are dirty, you change them because they are getting old. I think on LPG the oil eventually turns acid, but not sure.

Have fun...