The arrow exists because vehicle designs vary so much. Engineers have to balance packaging, manufacturing, crash protection, fuel-system requirements, heat management, and the existing vehicle platform. A choice that makes perfect sense on one model may be impractical on another, even when both vehicles come from the same company.

So the next time you wonder why one car has its fuel door on the left while another has it on the right, there is no mystery or prank involved. The location is simply where the engineers found the most workable route. You do not need to remember every model. Just look at the little arrow on the dashboard. The fuel door goes where the design allows it to work; the arrow tells you where to find it.