GM Service Manual Online
For 1990-2009 cars only

Caution: Your Compressed Natural Gas (CNG) vehicle should only be carried by flatbed because towing your vehicle with improperly positioned tow straps, hooks or chains can damage the fuel system and cause a natural gas leak. If the gas is accidentally ignited, you or others could be seriously injured. Do not tow your vehicle with the wheels on the ground.

Consult your dealer or a professional towing service if you need to have your vehicle towed. See "Roadside Assistance" in the Index of your owner's manual.