At our speeds you'd never know the difference but those tiny improvements can mean alot. For example if you remember the Monte Carlo SS Aero Coupe (built for NASCAR) which basically was the addition of a sloped rear glass instead of the square back typical of the day. This addition ONLY made a .05 improvement in the drag coefficient number. Sounds tiny and was even laughed at but to make that same gain in top speed at the time would have required an additional 50 horsepower. Try coming up with more 50HP within the rules of racing on a motor thats already at limits and all of the sudden that goofy rear window is pretty attractive. <img src="/forums/images/graemlins/smile.gif" alt="" />