Have you ever arrived at a gas station only to discover that your car’s fuel door is on the opposite side from the pump? It may seem random, but there is no universal rule requiring automakers to place the fuel filler on the left or right. Instead, its location depends on the vehicle’s overall design and engineering.

A car’s underbody contains numerous components, including the fuel tank, exhaust system, suspension, brakes, wiring, and structural elements. Engineers must arrange all of these parts safely and efficiently. The fuel-filler neck also needs a practical route between the fuel door and the tank, so one side may work better than the other.

Exhaust placement and heat management can also influence the decision. Safety is another major consideration because manufacturers must ensure the fuel system is properly protected during a collision while also meeting emissions and fuel-containment requirements. Manufacturing considerations can matter too, particularly when changing the fuel-door location would require major modifications to the vehicle’s structure or production process.

That is why even vehicles from the same manufacturer can have fuel doors on different sides. Each model may use a different platform or have unique engineering requirements. The driver’s side is not automatically preferred; sometimes placing the fuel door on the passenger side simply makes more sense for the vehicle’s design.

Fortunately, you do not have to remember where your fuel door is located. Check the fuel-pump symbol on your dashboard. A small triangle or arrow beside the symbol usually indicates which side of the vehicle the fuel filler is on. That tiny indicator can save you from pulling up to the wrong side of the pump.