Option 1: Material of car brake - This option is incorrect. Misch metal is not used in the manufacture of car brakes. Car brakes are typically made with materials such as cast iron or carbon composite materials.

Option 2: Smoke detectors - This option is incorrect. Misch metal is not used in the manufacture of smoke detectors. Smoke detectors typically contain a small amount of americium-241, a radioactive material, which is used to detect smoke particles in the air.

Option 3: Cigarette lighters - This option is correct. Misch metal is widely used in the manufacture of cigarette lighters. Misch metal, which is a mixture of rare earth elements, is often used in the flint of cigarette lighters to create sparks when struck against a rough surface, igniting the gas or fluid used for lighting a cigarette.

Option 4: Emergency lights - This option is incorrect. Misch metal is not used in the manufacture of emergency lights. Emergency lights typically use LED lights or other types of bulbs powered by batteries or electrical sources.

In conclusion, misch metal is commonly used in the manufacture of cigarette lighters, making option 3 the correct answer.