As with all makes and models of any vehicle, the 17 character Vehicle Identification Number (VIN) found on the dashboard or door jamb of your GM car or truck holds a wealth of information. The VIN can tell you where the car was built, at what plant it was assembled, its serial number, details about the vehicle's engine and even the fuel type. You can find the fuel type information in the eighth position of the VIN.
For GM passenger car vehicle models in years 2011 to 2012, an alphanumeric value in the eighth position in the VIN should alert you to the constitution of your engine, as well as the type of fuel which it runs on. A value of "E" indicates a gas engine, while an "H" signifies a gas/ethanol engine; a "Y" will show you that your car runs on diesel. Numerically, a "2" or "4" indicate you have a flexible fuel vehicle with a gas/ethanol engine. However, you may want to doublecheck with GM that your vehicle is in fact flex-fuel capable, because the VIN may not provide up-to-date information in that regard. Checking for specific makes within GM will also narrow down the types of engines and their respective fuel types: Cadillac and Buick passenger cars have a limited number of engine and corresponding fuel types, while Chevrolet has many more.
During the years 2000 to 2010, GM detailed VIN codes for passenger cars, light trucks and medium duty trucks; however, while it provided information on the engine type for the first two types of vehicles, it did not specify which types of fuels the engine used. It offered information on the number of cylinders, the liter capacity and fuel injection system, but does not state whether the car or light truck could use gas or ethanol. However, with regard to the VIN description of medium duty trucks, GM does indicate whether the medium duty truck's engine used gasoline or diesel.
Between the years 1981 and 1999, GM identified its passenger, light truck and multipurpose vehicles and medium duty trucks in much the same way as subsequent decades. The eighth position of the VIN gave information on the type of engine in the vehicle, but the exact fuel type was not consistently given for passenger cars. The fuel type of medium duty trucks, however, was provided in these years, i.e. the symbol "B" for a GM 6.0L 488L V8 gasoline engine for a medium duty truck in 1990.
In 1980 and earlier year GM cars, the engine and fuel type was not in the eighth position of the VIN, as were later models, but rather, in the fifth position. In the case of light duty trucks that year, the engine type was in the third position. Nonetheless, the fuel type for the engine was not specified during that time except in the case of medium duty trucks. GM models prior to 1972 are specified as vintage and require additional fees to decode the VIN.
