Im looking into the possiblity of a 2500 silverado Bi-fuel (runs on gas or Compressed natural Gas) 4x4. Aside from going to my local CNG fill up station i have not found a way to get current CNG costs at the pump. It is supposed to cost between 15% to 40% less than the equvalent in gasoline. But ive heard that natural gas prices have been on the rise reccently. If you fill up at a public CNG station in your area let me know what you are paying. Thanks Also, any opinions or experience in here on factory installed Bi-fuel pickups and SUVs?