Copper is a soft metal which is used in many applications in a vehicle, especially in the electrical system. Its low resistance makes it ideal for wires, and it was once a common material to make radiators out of due to its great thermal transfer properties.
Traditional spark plugs use a copper core due to it being relatively inexpensive and a good conductor. Even if a spark plug is not called a "copper" plug, it will still have a copper core, with very few exceptions.
Wires, such as the positive and negative battery cables shown at the left, are most commonly made out of copper due to it having a great cost-to-conductivity ratio. Aluminum is inexpensive, but doesn't conduct as well as copper, while gold and silver conduct much better than copper, but would be quite costly to make into wire.
Copper's high value (due to high demand) makes it highly desirable to recycle. In the middle of 2013, the rate for scrap copper was about one USD per pound with other scrap (such as copper wire with the coating still on it) or three USD per pure pound. The percentage of copper recycled is high, but not as high as lead.
Refined copper is difficult to make as pure as freshly mined copper. Copper scrap taken in can be melted to remove non-metal impurities, but the metal impurities have to be removed by getting the temperature right and/or skimming it off with the slag. Due to the need for low resistance in wires, most copper wiring doesn't use refined copper, which makes it slightly more expensive.
Video: Copper (by Periodic Videos)
Use In Alloys
Copper is the most abundant element in brass, and is also used in certain alloy formulations of steel.