Long ago, I posted a link to a URL that describes how the EPA does mileage testing...and get this, they don't actually measure the volume of gasoline consumed. Instead, they measure the emissions from the exhaust, and I guess there's some formula to figure out the mileage. How wacked out is that?!
Here's the URL (you'll need a .pdf viewer like Acrobat): http://www.epa.gov/oms/cert/factshts/gasmel.pdf
Here's the URL (you'll need a .pdf viewer like Acrobat): http://www.epa.gov/oms/cert/factshts/gasmel.pdf
