THE dedicated E-gas option on the Falcon costs $1400, which is what you need to recoup before you start saving money. My calculations, done after driving a dedicated LPG Falcon against a petrol one, suggest you will be in front after 20,000km, which I estimate to be a little more than a year's driving. That's a new Falcon, but it's going to be less with a used car because the market doesn't value the E-gas option, so you should be able to pick up a BA E-gas car for the same price as a petrol one. You're saving money from the start that way. Holden didn't have an LPG option in the VY, so any you find on theused-car market will be an aftermarket installation.