Almost every driver has been in this situation: the fuel light comes on, and you wonder how far you can really go before the tank runs dry. The answer depends largely on your vehicle’s gas mileage, fuel tank capacity, and driving conditions. Here’s what you need to know about driving on empty, the risks involved, and how to choose a car with the best gas mileage to avoid stressful situations. How Much Fuel Is Left When the Light Comes On? The amount of gas left in the tank after the low-fuel warning varies by make and model. For most cars, the fuel light comes on when there are about 2–4 gallons remaining. For example: Some brands, like Ford, trigger the