Have you ever pulled into a gas station and realized the 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 fillers on one specific side, so the location can vary depending on the vehicle’s design, engineering, safety, and manufacturing requirements.

A car’s underbody contains many important components, including the fuel tank, exhaust system, suspension, wiring, brakes, and structural parts. Engineers also need to find a suitable route for the fuel-filler neck while considering heat management, crash protection, emissions control, and the existing manufacturing process. As a result, one side may simply work better than the other for a particular vehicle.

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