There's already a product out there for non-OBD and/or carburated vehicles. If you go to a boating supply store/website you can get gps gauges that also have a transponder that you put in-line with your fuel line. These gauges will give very accurate speed, fuel flow, and typically have MPG readouts. Unfortunately I have yet to find one even close to the cost of a ScanGauge.
![Mad](/forum/images/smilies/mad.gif)