http://autospeed.com/cms/A_109741/article.html
They describe a different method for measuring aero drag. Not bad, but I wonder how accurate it is. Its hard to say if a MAF sensor's voltage is directly proportional to engine load. For example, say you get 1 volt @ 60 mph and you are using 10 hp to maintain that speed. Does .5 volts mean you are now using 5 hp to maintain speed? I wouldn't be too sure. But, it is a way to measure improvements.