A flex-fuel vehicle (FFV) is a car or truck designed to run on more than one type of fuel, specifically on gasoline or a blend of gasoline and ethanol. The most common ethanol blend in the United States is E85, which contains between 51% and 83% ethanol, with the remainder being gasoline. The vehicle's onboard computer system automatically detects the ethanol-to-gasoline ratio and adjusts the engine's timing and fuel injection to optimize performance.
The primary advantage of FFVs is fuel source flexibility. If E85 is significantly cheaper than regular gasoline in your area, you can save money on fuel costs. Ethanol is also a renewable resource, often produced from corn in the U.S., which can reduce the overall carbon footprint of your driving. However, it's crucial to understand that while E85 has a higher octane rating (typically over 100) which is beneficial for performance, it contains less energy per gallon than gasoline. This results in lower fuel economy (fewer miles per gallon) when running on E85.
| Fuel Type | Ethanol Content | Typical Octane Rating | Energy Content (vs. Gasoline) | Impact on MPG |
|---|
| Regular Gasoline (E10) | Up to 10% | 87-93 | 100% (Baseline) | Baseline |
| E85 | 51-83% | 100-105 | ~73% | 15-30% Reduction |
| E15 | 15% | 88 | ~97% | Minimal Reduction |
You can identify a flex-fuel vehicle by looking for a yellow gas cap, badging on the trunk or tailgate that says "Flex-Fuel," "E85," or "FFV," or by checking your owner's manual. The vehicle's VIN (Vehicle Identification Number) can also be decoded to confirm it's an FFV. Before you commit to using E85, check the availability of stations in your regular driving areas, as they are not as ubiquitous as standard gas stations. While most modern FFVs are engineered to handle ethanol's corrosive properties, it's always wise to consult your manufacturer's recommendations.
