Wagon wing mock up
 

Ok so on my 02 wrx is a rear spoiler which has a gap between the roof line and the wing, remove that gap reduce drag. First the material I plan on using is easyliner by ducktape, has anyone else used this material, it's cheap and comes in 20"x8' roll some less some more. The pictures should help more so here:

http://farm3.staticflickr.com/2818/9...90cb20a0_k.jpg

http://farm8.staticflickr.com/7449/9...d33a73c5_k.jpg

Any suggestions on removing the crease where it bends down to the glass would be appreciated. I've tried to pull it up higher so that it meets the glass closer to where the spoiler is mounted but it doesn't help. The more material there the better the drag will be reduced and handling increased, imo.

crease
 

If it weren't over plastic I'd say try a heat gun.But if the spoiler itself is a thermo-formed or thermoset plastic compound you risk ruining it by applying heat.
You might just tape it closed,do an mpg test.If you like the result,see if there's an online forum where others are working with that particular material.Sometimes You-tube will have videos of folks working with an assortment of technologies.Might find something.

Thanks, but it would be smooth its just the corners create a point. I think I figured out what I'm going to do, I'm going to wrap the spoiler first covering the gap b/n it and the roof then apply a second part to act as a partial kamback. It won't lower drag much but it will improve it from the softer edge, it should look good also and add to performance. Cars at the mechanic for the next week for a suspension upgrade and wheel bearings. I should have it fitted by the end of the month.

Flapping is bad so I'd suggest either use a more rigid material or otherwise frame and tension it.