Very nice! I like automotive projects, esp ones that do efficiency stuff.
Just curious though, why is the input being taken from the injector pulses rather than measuring the flow of fuel on the gas line? I know some cars have a bypass fuel system, but that could be handled pretty easily.
Not my project of course but if fuel consumption can be determined by the duty cycle of a fuel injector as shown that has to be a whole lot cheaper, simpler and more reliable then any kind of flow meter. Once the initial calibration constant values are known, it's a simple digital input pulse timing routine.
Lefty