Spoiler Vs. Wing

[Haifisch M3]

ever wondered about the difference between rear-wing and rear-spoiler?

interesting 2010 article

link

This weekend at Martinsville Speedway, the spoiler makes it return onto the back of Sprint Cup cars, eliminating the wing. The wing design made its debut at the 2007 spring Bristol race and made its exit at last weekend’s race at the same track.
Prior to its elimination, drivers and fans alike did not care for the wing. Most of the reasons were in the cosmetic category in terms of car design appeal. Other reasons were more thought out in regards to affecting a car’s handling ability during a race, particularly in passing cars or making the car looser on the track.
Bernie: Hopefully, with the extra downforce that the car with the spoiler generates, it will improve the racing so people can race side-by-side and it will make it more exciting again.

Dan: Will going from the wing to spoiler stop cars from getting off the ground?
Bernie: The wing was a very low lift aero foil and before the new car got implemented, NASCAR did lift-off testing with both the spoiler and the wing, and, at the time, there was no difference in the lift-off numbers. After the Ryan Newman accident last year at Talladega, NASCAR went back to the wind tunnel and did some more lift-off testing work with the wing and the spoiler and, again, there was very, very little difference. So, really, the reason why the cars fly is not because of the wing, and going back to the spoiler is not going to prevent that. The biggest problem is when the car turns, you get all this air that goes into the back, underneath the rear bumper and the underside of the car, and that just causes the rear of the car to lift.

the obvious question:
does a vertical, flat piece of aluminum at the end of the trunk-lid work as well or better than our fancy wings?
seems to be good enough for the nascar boys running at 200mph

[Pat533i]

The wing will provide downforce, rear spoiler or gurney flap only reduces drag.

edit* the spoiler/flap can also reduce lift from drag, so I guess provide some downforce.

I'm no expert and really have no idea what I'm talking about.

[TXBDan]

Both create downforce, wings are just much more efficient at it.