Cars are environmental objects on the various multiplayer maps and single-player levels in the Call of Duty series. They can either take the form of civilian cars (Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 2) or trucks (Call of Duty: World at War). Cars are littered across the maps (usually on the streets) and can easily be destroyed with explosives, light machine guns, etc. When cars sustain enough damage, they will catch on fire. Cars on fire will sustain constant damage until it explodes. This puts the player at great risk whenever they decide to hide behind a vehicle and can cause great frustration, especially if they were killed in either the multiplayer or singleplayer levels due to this.
In Multiplayer, the last player to damage the car gets any kills from it. Therefore allies are unaffected by explosions from cars as long as the player shoots them last. Likewise, in hardcore they may incur teamkills for no apparent reason if they leave flaming cars around. Kills by cars do not count towards the Danger Close Pro challenges.
Here is a list of Multiplayer levels containing destroyable cars.