The purpose of any car's heat shield is to do exactly what its name implies--to shield various parts of the car, the driver and the immediate environment from the heat generated by certain automotive systems.
With regard to standard automobiles, the term "heat shield" generally refers to plates that insulate parts of the exhaust system, which steadily generates high temperatures when a car is running.
Regular automotive heat shields are made of metal; many feature fiberglass between metal sheets. On specialized or high-performance vehicles, shields may include carbon composite or other lightweight high-tech materials.
Heat shields keep the exhaust system from heating up the floorboards and other adjacent car parts, and also protect tall grass or other flammable items that might come into contact with the underside of a vehicle from incendiary temperatures.
Some cars may have additional heat shields to insulate other parts that generate inordinate heat, such as the radiator or a turbo system.
Car enthusiasts go back and forth over whether or not heat shields are truly necessary, as they sometimes tend to rust, rattle, crack and come loose.
