We have a 1991 Dodge Dakota 4X4 (5.2L)truck that we had converted to CNG (dual fuel really) right from day one.. It has had a few problems with it mostly because it was a "new" thing.. We only get about 100 to 130 Km to a "fill" depending on where, how and who drives it.. We also own a compressor that allows you to re-fill your vehicle right at your home, right off your own gas meter, all that is needed is the gas connection and a 240V 15A circuit.

Problems wise it was mostly electrical, the conversion was very "hack", and the burning of Natural gas in that engine was very hard on the valves for some reason, BUT it did burn very clean. Our 1994 Dodge Caravan (3.3L)had no engine or electrical problems (except for the sheer lack of horsepower), it was converted to CNG from day one as well, that vehicle has since been sold.
The only drawback with owning the compressor is it needs a "rebuild" every few thousand hours at a price of $900 Cdn. but in the long run, CNG is still cheaper than gasoline.

Gasoline prices here in Southern Ontario range from $0.83 to $0.85 /L (87 octane) from what I saw today in my travels.. that seems like a "deal" to most of us considering it was up over a dollar for the longest time, spiking at $1.34 once! Hard on the pocketbook if you drive even a small compact car, but in my case I am the proud owner of a 2000 Dodge Ram 2500 4X4 (5.9L Gasoline motor)... 134 L fuel tank.....1 tank every week and a half..

Boy, do I ever wish it was a Diesel! [Linked Image]

A.D