Have you ever wondered why some cars have their fuel door on the left while others have it on the right? Surprisingly, there is no universal rule requiring automakers to place it on a particular side. The decision depends on the vehicle’s design, including the fuel tank, exhaust system, suspension, wiring, and structural components beneath the car. Engineers must find a safe, practical route for the fuel line without interfering with other systems or compromising the vehicle’s structure.

Moving a fuel door is also more complicated than it might seem. It can require changes to body panels, fuel lines, and manufacturing processes, making it easier for automakers to keep an existing design when it already works. Safety plays an important role, too, as fuel systems must contain fuel, control fumes, and meet crash-protection requirements. These differences explain why even two vehicles from the same brand can have fuel doors on opposite sides, depending on their platforms and engineering layouts.

Fortunately, there is an easy trick to help you avoid pulling up to the wrong side of a gas pump. Look at the fuel gauge on your dashboard and check for a small arrow or triangle beside the fuel-pump symbol. On most vehicles, it points toward the side where the fuel door is located. Instead of memorizing every car’s design, you can use this simple feature whenever you drive an unfamiliar vehicle. What seems like a small design difference is really the result of practical engineering decisions—and one tiny dashboard arrow makes it much easier to navigate.