All you need to do for 45% over EPA is aeromod the living sh*t out of it and take a nice long road trip at 55mph. See if you can get some high-adhesion painter's tape to hold wheel skirts, grille blocks and a kammback on. Pull the mirrors off- they should be bolted on, making re-installation easy. Make coroplast wheel covers and zip tie them to the spokes. Make a lawn edging air dam. You're going to need to pull out all the stops.
To put it in perspective, this got 46% over EPA Hwy (41 actual, 28 epa) on a sunny 50 degree day, going about 62mph over 400 miles. No P&G... only coasted on a few long hills. Little drafting since I was passing most people.
New Air Dam by
Tyler Linner, on Flickr