The use of E85 as a fuel for vehicles is discussed in this chapter. E85, a blend of 85% ethanol and 15% gasoline is a liquid fuel that can be utilized in a wide variety of vehicles. The use of E85 has been encouraged because it dramatically reduces exhaust and greenhouse gas emissions. Additionally, the ethanol used can be derived from renewable sources. In order to use E85, the vehicle must have a spark-ignited engine. Furthermore, this engine must be adapted to accept E85.