Instant MPG gauge for OBDII

This is very simple. I want to know how to make a simple (& cheap) instant MPG meter for a vehicle fitted with OBDII (i.e. most recent vehicles) that will plug into the OBDII port.

capt.tagon8 years ago
http://ecomodder.com/forum/showthread.php/obd-mpguino-gauge-2702.html

Work in progress, you have four different protocols, determine which your car uses, interface for that then you extract information to calculate MPG.