The lack of a visible gas cap on your 2015 Ford Explorer is due to a feature called "capless fuel fill." This feature is designed to provide convenience and prevent fuel vapors from escaping into the environment.

Instead of a traditional gas cap, your vehicle has a capless fuel fill system. This system consists of an inlet funnel and an integrated sealing system. When you open the fuel door, you will notice a funnel-like structure. This funnel is where you insert the fuel nozzle during refueling.

When you insert the fuel nozzle, it opens up a flap inside the fuel filler neck, providing access to the fuel tank. Once the refueling is complete and you remove the nozzle, the flap automatically closes, sealing the fuel system to prevent fuel leaks and minimize evaporative emissions.

The capless fuel fill system offers several benefits. First, it eliminates the need to worry about misplacing or forgetting to tighten the gas cap, as the opening is always accessible. Additionally, it reduces the chances of fuel odors escaping and prevents fuel spills during refueling.

However, it's important to note that even though your car does not have a traditional gas cap, the fuel filler neck still has a sealing system that can wear out over time. If you notice any issues with the fuel fill system, such as difficulty inserting the nozzle or fuel leakage, it's recommended to have it inspected and repaired by a qualified mechanic to ensure its proper functioning.

Overall, the capless fuel fill system on your 2015 Ford Explorer is a convenient and environmentally friendly feature that eliminates the need for a traditional gas cap.