Rumdog - I have designed many wings (or spoilers?) of that style
ChazInMT - You're more correct than I'm sure you could ever imagine haha. I have two different setups, one to test downforce and one to test drag. The one for downforce works beautifully, but the drag one has been having issues of not reading enough on the force gauge to see any differences. With any luck this issue will be fixed by next week.
kach22i - I actually did test a ducktail for one of my designs. Look up a Rocket Bunny 240z to see a similar style wing. Strangely enough at both high (40 mph) and low speed, the spoiler zeroed out the lift of the car. For a good side view, google "civic coupe dimensions".