Why Some Cars Have Gas Caps On The Left (And Others Have Them On The Right)

One of the most confusing aspects of refueling, other than some new cars not having gas caps at all, is the inconsistency of the fuel door placement. They are either on the left or right side of the vehicle, even for cars originating from the same manufacturer. This can become a frustrating ordeal, especially if you're renting or borrowing a car where the gas cap is located on the opposite side of what you're accustomed to with your vehicle. So what's the reason for manufacturers making such a switch up?

The origins of this design goes back to the earliest days of the automobile. Back then, it was standard practice for car fuel doors to be located on the back of the car behind the license plate. At the time, it was viewed as the most convenient way for drivers to fill up as they could do so comfortably from either side of the vehicle. However, the safety of this placement would come under scrutiny as time went on. In the instance of a rear-end collision, having the gas tank be ruptured could lead to fires or even explosions. Given how common this accident type is, it became mandatory for all cars to have their fuel doors located on the side. 

The fuel door will always be on the widest section of your car, as this keeps it separate from fuel lines and wiring. However, no regulation is in place regarding which side this must be on. Still, that hasn't stopped people from presenting strong theories as to why. 

It's easy to imagine how much easier life would be knowing that any car you drive will have its gas cap in the same place. This would seemingly make things easier at the gas station since you would never again need to awkwardly reposition your vehicle after accidentally presenting the wrong side to the fuel pump. While this may sound nice in theory, it's largely for this reason why the positioning of fuel doors lacks consistency. 

As you likely know, the side of the road and placement of the driver differs between countries. In the United States, for example, drivers are expected to keep to the right side of the road with the driver's seat being on the left. Gas stations that allow drivers to enter from the right side and have pumps that are easily accessible from the driver's side usually see more business. Giving all cars uniform fuel door placement could potentially create congestion at gas stations if all pumps were designed to only cater to one side of the vehicle, especially during peak hours. Positioning fuel doors at different locations gives drivers more options to easily access a pump without needing to wait in long lines or make awkward turns to reposition their car. 

Most modern cars possess an indicator light on the dashboard in the shape of a gas pump. Next to this, there will usually be a small arrow or diamond pointing towards the side where your fuel door is located. Don't ignore the gas light if it comes on, as it's not safe to drive with it on.