Self adjusting spoiler
As a car accelerates, electronic sensors send data to a ecu which uses algorithms to judge how fast the car is going, and tells it to the speedometer. If you can splice a wire into that same ecu port, you can create a spoiler that rises accordingly to the speed that its going. E.g. if a car is going 30 miles an hour, a spoiler might have a 12 degree incline (just random numbers) that’s fine if you only go 30 miles an hour, but if you go faster you wont produce enough down force; so a self adjusting spoiler will change it’s angle in a linier proportion to the speed of the car. This self adjusting spoiler will move by a pneumonic actuator controlled in the same way the speedometer is controlled.