I've just joined the site (well done... Looks great). I was somewhat surprised to find there is no report for the co2 emissions of my driving. Is this something you might.consider?
This guidance on calculating the emissions from the EPA might be a helpful starting point -
http://www.epa.gov/otaq/climate/420f05001.htm
Car emissions are for many people an important aspect of their 'driving profile' so I think this would be a greet enhancement to Fuelly.
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