There are many conversions being done in Canada. I know of whole taxi fleets running on propane. The guy doing the conversions is around the corner from me (only works on Crown Victorias and pickups though). I have a buddy who had his pickup converted to CNG. However there aren't many filling stations selling natural gas; propane is much more readily available. Filling up with natural gas at home sounds interesting, but I understand it can take 8 hours. Demand for propane has been fairly stable, hence the price. Natural gas is widely used for home heating and the market forces acting on it are completely different than those affecting propane. Who knows where the NG price is going.