ScanGauge worth it?

[MetroMPG]

Originally Posted by jamesqf

was under the impression that they apply various algorithms to estimate fuel consumption from the OBDI-accessible info, while the Honda OEM display computes fuel consumption by adding up the amount of fuel the ECU tells the injectors to deliver.

Yes, that's what the SG does (and why it doesn't do as well with lean-burn equipped engines).

The MPGuino directly monitors an injector signal, so it's more like your car's MPG system. Lean burn doesn't faze it, since it's just counting injector pulses.