The history of Automobile spoilers was way back from the 1960's, when race cars still looked more or less like cars on the normal street. Custom style spoilers were actually put to use by NASCAR when racing teams petitioned for allowing the very unstable Dodge Charger to create a downward force on the rear side, thereby making it less likely to lift off. So, one can define spoiler as an aerodynamically designed device used on a speeding vehicle to disrupt unwanted air movement across the vehicle while gaining higher speed levels. So the spoilers in street legal vehicles are influential over fuel efficiency by reducing the drag and also increasing the looks of the car to a certain extent.
Spoilers can be classified into two types - front spoilers and rear spoilers. Front type spoilers are attached just below the bumper. Both these types function similarly. Front spoilers push away airflow to the underside of the chassis where the coefficient of drag is quite low. They have different terms of their own like chin spoiler and air dam. They can also be attached to the sides and are called skirts. The Front bumper simply displaces the flow of air towards the underside reducing lift and drag. The rear spoiler on the other hand simply influences the fuel economy by reducing drag. Spoilers are more efficient with racing cars, even though they are equipped with a quite stiff chassis and an equally rigid suspension to help high-speed maneuvers spoilers can be of great use considering its function of delaying separation of airflow and displacing airflow to gentler slopes across the car.
Spoiler materials are majorly of four types ABS Plastic, Silicon, Fiberglass and of course Carbon Fiber. ABS Plastic is a type of material for spoilers made by casting with different admixtures, which gives plasticity to the otherwise frail material. Fragility is the main disadvantage, which increases with time due to volatile phenols evaporating. Fiberglass spoilers are again cost cutters, which are fiberglass cloth filled with thermosetting resins. It is more efficient than ABS but is not very profitable for big scale productions because of heavy labor cost. Silicon spoilers are a recent invention, which is made of silicon organic polymers and are phenomenal because of its plasticity. They are also more durable and give high product life. Carbon fibers are one of the most efficient materials in making effective spoilers but are highly expensive and unprofitable due to manual labor.