
The most reliable way to tell if your car takes E85 fuel is to check for a flex-fuel badge or label, consult your owner's manual, and look for a specific vehicle identification number (VIN) pattern. E85, a blend of 85% ethanol and 15% gasoline, requires a Flex-Fuel Vehicle (FFV) with an engine and fuel system designed to handle its corrosive properties and different combustion characteristics. Using it in a standard gasoline car can cause significant damage.
Start with the obvious visual checks. Many FFVs have a badge on the trunk or tailgate with terms like "FlexFuel," "E85," or "FFV." Open the fuel door; a yellow gas cap is a common, though not universal, indicator. There should be a label inside the fuel door that explicitly states the fuel types accepted, often reading "E85/Gasoline" or similar.
The owner's manual is the definitive source. Check the index or fuel section for "E85," "Ethanol," or "Flex-Fuel." If you don't have the manual, you can often find a digital copy online using your car's make, model, and year.
For a more technical verification, you can decode your VIN. The 8th character often indicates the engine type. While not a universal standard, a common pattern for many GM Flex-Fuel vehicles is the 8th character being a "Z". You can use a free online VIN decoder or contact a dealership with your VIN for confirmation.
| Verification Method | What to Look For | Key Consideration |
|---|---|---|
| Exterior Badge | "FlexFuel", "E85", "FFV" on trunk/tailgate | Not all FFVs have prominent badges. |
| Fuel Cap & Door | Yellow fuel cap; label stating "E85/Gasoline" | A yellow cap is a strong hint but not a guarantee. The label inside the door is more reliable. |
| Owner's Manual | Specifications for "Fuel" or "E85" | The most authoritative source for your specific vehicle. |
| VIN Decoding | 8th character (e.g., "Z" for many GM models) | Patterns vary by manufacturer; use a reputable decoder or dealer for accurate info. |
| Door Jamb Sticker | May list "FUEL: E85" or "ETHANOL" | Check the driver's side door jamb sticker for fuel information. |
If all else fails, a mechanic can quickly identify an FFV by the presence of an ethanol content sensor in the fuel line. Never put E85 in your car unless you are absolutely certain it is an FFV.

Pop open your fuel door. If you see a bright yellow gas cap, that's your first big clue. But don't stop there—look for a sticker inside that specifically says the car can use E85 or is a Flex-Fuel Vehicle. That sticker is the real confirmation. The yellow cap alone isn't a 100% guarantee, so always double-check.

Grab your owner's manual and look up "fuel" in the index. It should clearly state whether your vehicle is a Flex-Fuel Vehicle (FFV) approved for E85. If you bought the car used and don't have the manual, you can almost always find a free PDF version online. Just search for "[Your Car's Year, Make, Model] owner's manual." The specifications section will give you a definitive answer.

I always tell my neighbors to check the VIN. That's the Vehicle Identification Number on your dashboard. The 8th character can tell you a lot. For instance, on many Chevrolets and GMCs, if that character is a "Z", it means it's a flex-fuel model. You can find free decoders online or just call your local dealership's parts department—they can confirm it for you in seconds based on that VIN.

Beyond the badges and stickers, a real car guy will look under the hood. Flex-fuel cars have an extra part called an ethanol content sensor in the fuel line. It's a small module with wires coming out of it, usually located near the fuel filter. If you see that, you're good for E85. But if you're not comfortable poking around, just stick to the manual and the labels. It's not worth the risk of guessing wrong.


