Chances are, you know exactly where your car’s steering wheel, engine, and lights are located. You probably also know most design features in your vehicle serve a functional purpose. So, why aren’t all gas fillers put in the same place? And how does an automaker decide where to place the gas tank and filler?

Why don’t all cars have the same tank and filler placement?

There seems to be a general consensus when it comes to most auto mechanics. We can agree on where a fuel filter should go, where the spark plugs belong, and more. When it comes to the gas tank, however, no one seems to agree. There are plenty of places we can agree a fuel filler should not go, but how does an automaker decide which side to put it on?

While there isn’t any concrete rule when it comes to which side the tank will be on, certain factors determine how a company makes that decision. According to Jalopnik, fuel fillers on the passenger side (right) can mostly be found in vehicles made by “continental European carmakers and many American ones.” Fuel fillers on the driver side (left) are mostly found in vehicles made by Japanese companies, with exceptions to every rule. Variations on the side can exist within the same company. 

So, choosing the side you fill up on isn’t just determined by which company made it. According to Allstate, placement of a fuel filler is a factor most generally determined by tank design, location, and underbody design. For instance, cars that use a cable-operated internal release for the filler on the driver-side will see the fuel filler on the same side for convenience.

Fuel fillers can also be placed on a certain side due to other essential components within the car that require specific locations. Companies will also choose a particular side after weighing convenience against safety.

Many companies will pick a side based on the vehicle’s location, too. In order to keep drivers and consumers from having to fill up on the side of danger, many companies will put the fuel-filler on the side of the driver, whether it is left or right. This keeps you from being exposed to traffic.

The importance of proper gas tank placement

Are there any solid rules when it comes to gas tank and fuel filler placement? Laws do ban certain placements. Because fuel is flammable and dangerous, you cannot fill up in the most convenient spot in your car. Putting the fuel filler in the center of the vehicle (accessible via trunk or hood) seems to be most convenient. But it could end in a fiery disaster in the event of a simple fender-bender.

It is also illegal to place a fuel filler near any extreme outer edge of a vehicle. In fact, according to Readers Digest, current regulations dictate the filler “be at the widest part of a car, inboard of any crumple zones, and safe from dripping onto any hot exhaust bits or electrical wiring.”

While many wonder why we don’t just choose one side for our fuel fillers, the people at PBS point out that if every vehicle had a fuel filler on the same side, gas station equilibrium would be dismantled. So for now, we’ll have to settle with finding that fuel-filler dummy light to remind us which side to fill up.