Was leafing through my April issue of IEEE Spectrum when a photo of the
MPGuino along with some OBDI wire hacking caught my eye... lo & behold, it was a Hands On column on how to monitor fuel mileage on a 1997 Geo Metro by one of the senior editors! Even includes a link to the Ecomodder.com wiki pages!!
Wonder if the author David Schneider is a member here... ?
See
IEEE Spectrum: A Fuel-Economy Gauge for the Rest of Us