well since everyone else want to put in their opinion i will too. a spoiler no matter how big will make a difference. take for instance the newer carerras and 911s that have auto adjusting spoilers on the rear of the vehicle. they are very very small and were engineered with the vehicle to make a big difference. now if you really think about this no matter what platform you have whether you have fwd or rwd the weight of the vehilce is loading the suspension regardless. im sure most of you have felt a car start to float at very high speeds down force would help. i dont think any downforce on the rear end would make any difference on a car going 60 or more. in fact i think it would keep the back end in place a little more and maybe even reduce a small amount of roll on the vehicle since there isnt dead weight just drag pushing the rear down. as far as not needed off the line, what spoiler is. not even the rail drag cars use a spoiler for that. now for the shopping cart wings? they in theory would work but think of the consiquences of placing that type of pressure on a flimsy sheetmetal trunk lid. how about some nice dents and wrinkles. if there was a nice looking spoiler on the market that didnt look super futuristic jet fighter combat wing id buy it. along with a chin spoiler for trying to reduce undercar air flow.
