[aerohead]

Scott,sorry,as Darin says,I'm self-administering a big head slap.I've awakened now,and pulled the barn out of my eyes and realized you have wheels,not wheelcovers to modify.Isn't literacy a wonderful thing! Anyway,gee,those are beautiful alloy wheels.Too bad there isn't something that would just pop in to the openings.And not to shoot down your Bondo idea,here's a thought.If you're confident with the baseline mpg for the car,tape over the openings and test for improvement.If your pleased with the contribution the closed wheels make,then your good to go with the mods.If you go with the Bondo,you'll want good adhesion,so the "attachment" perimeter of the holes will have to be clean and wax free,and perhaps roughened a bit with say a 3-M Scotch-brite pad,to aid with bonding.If I were doing it,I would carnauba wax the face of the wheel around the perimeter of each opening to prevent Bondo from adhering there.Then I would wax sections of aluminum pie pan or other such light,smooth sheeting to form a "dam" at the outside of each opening,and tape them over the openings from the outside of the wheel with a very sturdy tape.With the wheels removed,I would measure out equal volumes of bondo( estimated to create your plugs),and work one at a time,adding in and mixing the MEK Peroxide paste hardener,one batch at a time.When you have a uniform color in the mixture,you can scoop the mix into the opening,and use whatever is handy to gently push it into place.Move on to the next opening and repeat 'til your done.Work with good ventilation as MEK is poisonous! The Bondo,being polyester based,has a very short pot-life and will gel in a matter of a few minutes.Un -waxed paper cups and popsicle sticks can be used to make the batches."tools" can be cleaned with acetone.Wear gloves! After the Bondo has gone off,you can peel away the dams to expose the raw hardened filler.Minor voids or imperfections can be smoothed out with skim coats of the Bondo.Follow label directions for sanding,priming and painting.Auto stores should have spray paint that will match the original metallic silver of the aluminum.