2000 voyager built-in MPG vs. OpenGauge/MPGuino

[rkhanso]

I have a 2000 Voyager minivan that has the factory MPG thing up in the headliner. It just shows instant and average MPG. It appears this thing is pretty accurate for average MPG. I was thinking about trying to build an OpenGague for this vehicle, but wonder if it's worth the effort (electrically/electronically capable, but something like this is stretching my abilities)

I realize this is subjective, but....is it worth the extra info to build the OPenGauge/MPGuino thing to squeeze extra mileage out of the van, or is the factory MPG thing sufficient?