What are the benefits of using a single wire system in automobiles?

In the automotive electronic system from the power supply to the electrical equipment connected to only one wire, and use the car chassis, engine and other metal bodies as another common wire.

Benefits:

Because the single-wire system saves wires, the line is simplified and clear, easy to install and maintain, and electrical components do not need to be insulated from the car body, so the modern automotive electrical system is commonly used in the single-wire system. But in special circumstances, sometimes also need to use the two-wire system.