Back in the 80's NZ's government actually subidised the installation costs for alternative fuel conversions. As result many cars were converted usually to run dual fuels, including Minis and 1200s!! Govt Dept fleets ran hoards of 6 cyl sedans that ran either LPG or CNG. My Dad even had his brand new 84 Honda Accord converted to CNG. As the fuel crisis died off conversions were less popular and slowed to a trickle. There was a clever ignition box produced call a dual curve ignition which allowed different advance setting when switching between petrol and gas. Almost all of the original gas filling equipment has now been pulled out , reconditioned and shipped to Malaysia. It's a shame really because it was the way to go.