[dongs]

I recently bought a 2002 cavalier with the 2.2 ohv motor and an auto trans, unfortunately the only cav I could find with a manual trans was in need of a new clutch and the owner wouldn't budge on price.
Epa highway mpg is 33 and my last couple tanks have been coming in just under 30. The car was reasonably well cared for but it's got nearly 160,000 miles on it. I ordered a new upstream oxygen sensor the other day since it looked like the original sensor was still in there and I couldn't find anything obvious that would be hurting mpg. And just to note I do drive gingerly and use some hypermiling techniques. The car is bone stock and I got it as a cheapo commuter to get me through my last year of college cheaply
I've been considering some aero mods and wanted to get some ideas/suggestions on where to start. The stock bumper cover has a lot of 'vents' on it so I was thinking of starting by blocking those off temporarily with tape until the weather gets warmer and I can fashion something out of fiberglass. I'm probably also going to get rid of the antenna since I don't use the radio anyway. I've been thinking about rear wheel skirts as well. I don't have the space or desire to do anything too radical like a boat tail or anything but I do want to do some modest things to squeeze a few extra mpg out of it. The next oil change is going to be with the lowest weight synthetic I can get away with.
What are your opinions? Would those aero mods amount to much? If making wheel skirts and a new bumper won't do a whole ton then I'd rather save the time and money and stick to using cheaper materials like cardboard and tape.