I take it this is the same as lpg. if so along as the engine suitable and its fitted correctly id go for it. i have had friends who had lpg fitted to a range rover, x5, 550i, s500, r32 and Porsche cayenne 4.2 and none of them have had issues when fitted correctly. the x5 had issues but turned out the installer hadn't set it up correctly and once it was corrected it ran fine. the mpg also increases aslong as the gas itself is cheap although the limited range might be an issue as I know some where only getting 200-250 out of a full tank due to the car having a small lpg tank