http://www.popularmechanics.com/cars/how-to/maintenance/should-you-convert-your-car-to-natural-gas http://www.popularmechanics.com/cars/how-to/maintenance/shou.

http://www.popularmechanics.com/cars/how-to/maintenance/should-you-convert-your-car-to-natural-gas http://www.popularmechanics.com/cars/how-to/maintenance/shou... The lower-pressure gas travels to the engine, Chrysler's flex-fuel-capable Pentastar V-6. A flex-fuel engine is important, since it has hardened valves and valve seats, which are necessary for CNG operation. Suggests there is something to worry about in a conversion for regular cars.