By the way, I started researching this subject a while ago... I didn't get far enough, but here are some resources I found while I was at it:
http://www.nrel.gov/vehiclesandfuels..._emissions.pdf
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf
[EDIT: Sven7's antivirus flagged that last file. Scroll down to find my link to a PDF-printed version.]
Need... more... time...