How many mpg did your brand new car gain when broken in?

[oldtamiyaphile]

The car's ECU knows what the AFR is, the OBD gauges don't. That's why the onboard gauge is actually more consistent than than any OBD gauge. The onboard gauge might be 0.2l/100km optimistic (as it is in my Trafic and Prius), but that's better than OBD gauges that go +/- at random as they only have the MAF sensor to go by.

I drive off the onboard instantaneous display, SG is great for it's automatically resetting short trip meter (even if it's only semi accurate), and gives me a load gauge and water temp - that new cars usually omit.