There is no industry rule requiring every fuel door to sit on the same side. Automakers choose its location based on the vehicle’s overall engineering. Beneath the floor are the fuel tank, exhaust, suspension, wiring, brakes, and structural components.

Engineers must route the filler neck from the outside door to the tank without interfering with heat, crash structures, or a crowded underbody. On one model, the cleanest path may be on the driver’s side. On another, the same manufacturer may choose the opposite side because the exhaust, spare-tire well, or frame rails leave fewer options. Manufacturing also locks much of that decision in place. Moving a fuel door can require new body stampings, different fuel lines, and changes to the assembly process.