Originally Posted by D88
I think it's obvious that a rear spoiler does not provide enough downforce!
Rear spoilers are only functional at 150mph+ and on rear wheel drive cars. The chances of you getting up to 150 here is pretty slim.
So, every car you see on the street with a spoiler is just for show. I do admit, there are a lot of cars that look better with a FACTORY STYLE SPOILER, not one of those 4 foot high aluminum siding wings.
On a front wheel drive car, you would need a diffuser, like fins, slats to guide the air straight off the back of the car and keep the car in a straight line.