Unless you drive an electric vehicle, stops at the gas station happen frequently. But regardless of how many times you pull up to the pump, there’s always a moment when you don’t know or forget which side the gas tank is located. That’s especially true for rental cars. But among modern vehicles’ many features is one you might have never noticed.

There’s a dashboard indicator that takes the guesswork out of locating a car’s gas tank.

Vehicles with gas tank indicators

Most vehicles that are 10 years old or newer offer this convenient feature. Once you find the gas tank indicator on your car’s dashboard, you’ll wonder why you never noticed it before.

Located next to the gas pump icon on the dashboard instrumentation is a small triangle-shaped arrow. It points in the direction of the side of the car where the gas tank is located.

This simple dashboard indicator takes the guesswork out of pulling up to the pump. It helps you avoid straining your neck and eyes to see where you should fill the gas tank.

Older vehicles lack this hack

This dashboard indicator is helpful, especially when renting a vehicle or borrowing a friend’s car. Knowing ahead of time which side the gas tank is on helps alleviate frustrating stops at the gas station.

However, if you’re driving a vehicle older than 10 years, you might be out of luck. AutoGuide.com explains that most older-model cars don’t have an arrow. But “some still have a hose on the little gas pump indicator that shows which side the tank is on.”

Why aren’t all gas tank doors on the same side?

Gas tanks used to be located behind the license plate at the rear of vehicles. But automakers realized the location proved an inherent risk if the car was involved in a rear-end collision. After multiple cases involving explosions on impact, the practice of rear-placed gas tanks ended, Automotive News reports.

There’s speculation that manufacturers don’t put fuel tank doors on the same side to reduce crowded lines at the pump. Gas station efficiency probably isn’t on automakers’ high-priority list, so the more reasonable explanation is likely convenience.

In the United States, drivers sit on the left side of the car traveling on the right side of the road. It only stands to reason that it would be easier to pull closer to the driver’s side to access the pump. Nissan communications manager Steve Yaeger told theAllstateBlog in 2018: “The placement of the fuel door is mainly a factor of fuel tank design, location, and underbody packaging.”

There really is no proven rhyme or reason why manufacturers place gas tank fillers where they do. The only thing standard on newer vehicles is the placement of the dashboard indicator next to the gas pump icon.

So the next time you’re uncertain which side to access your car’s fuel tank, look for that helpful little arrow to show you the way.