Have you ever pulled into a gas station and found that your car’s fuel door is on the opposite side from the pump? There’s actually a practical reason for this. Automakers are not required to place fuel doors on one particular side, so engineers choose the location based on the vehicle’s design, engineering requirements, safety considerations, and manufacturing process.

A car’s underbody contains many important components, including the fuel tank, exhaust system, suspension, wiring, brakes, and structural parts. Engineers need to fit everything together safely and efficiently, while also finding a suitable route for the fuel-filler neck. Exhaust placement, heat management, crash protection, emissions requirements, and the existing vehicle structure can all influence which side is chosen.

Manufacturing can also play a role. If moving the fuel door would require significant changes to the body, fuel lines, or production process, keeping it in the existing location may make more practical sense. That’s why even vehicles from the same manufacturer can have fuel doors on different sides, and the driver’s side is not automatically the preferred indicates which side of the vehicle the fuel filler is located on. So next time you stop for fuel, that tiny dashboard choice.

Fortunately, you don’t have to remember which side your fuel door is on. Just look at the fuel-pump symbol on your dashboard. A small triangle or arrow beside the symbol indicates which side of the vehicle the fuel filler is located on. So next time you stop for fuel, that tiny dashboard indicator can save you from pulling up on the wrong side.