Yes, all of the Call of Duty: Modern Warfare games on PS3 have a singleplayer campaign. Some of the campaign modes have a co-op mode, but I'm not sure which of the games has this. Call of Duty 4: Modern Warfare has singleplayer and multiplayer.

Call of Duty 4: Modern Warfare - Playstation 3.

There is also less wear and tear in engines as CNG burns completely, which also helps in saving the expensive costs of part replacements, oil changes, tune-ups, etc. It is also observed that the life of lubricating oils is also increased, as CNG does not contaminate and dilute the crankcase oil.

Over the past one year, there has been a spurt in the price of CNG, led primarily by the hike in the prevalent natural gas price; factors such as increase in blending cost and depreciation of the Indian Rupee also contributed to multiple price hikes.