The BMW 7 Series' fuel tank is made of plastic, not steel. This choice was based on multiple considerations to ensure optimal vehicle performance and user experience.

A major advantage of plastic is its lightweight, which effectively reduces vehicle weight and improves fuel economy. Furthermore, its excellent plasticity allows for tank designs that more closely fit the vehicle's interior, effectively utilizing space. Plastic is also highly corrosion-resistant and rust-resistant, significantly extending the tank's lifespan.

Plastic fuel tanks also offer the advantage of being less susceptible to sparks and static electricity, significantly enhancing vehicle safety. The BMW 7 Series chose a plastic fuel tank to ensure the proper functioning of the fuel system and prevent fuel contamination caused by rust.

In addition to the material choice, the BMW 7 Series also features a unique fuel cap opening method. Instead of a traditional physical button, it utilizes an electronic remote key for central locking. When the vehicle is unlocked and the key is nearby, a simple press of the fuel cap automatically opens. This convenient and quick opening method enhances the user experience.

It's worth noting that common ways to open the fuel cap include an in-car switch and a push-button. The switch can be found in various locations, including on the floor panel to the left of the driver's seat, on the left front door panel, or on the center console. It's labeled like a gas pump, and the engine must be turned off before refueling. While the push-button opening method is convenient, the central locking system should be engaged when not refueling to prevent the fuel cap from opening accidentally.