[Mario_Marques]

"No, there is no trick. I think the IAT resistor does not work for Ecomoding-style of driving. The resistor makes a fake IAT temperature. The scangauge has a formula that depends on a real IAT temperature. It calculates an MPG that is not real because the data is not real (GIGO). That is my theory. Here is a version of the formula that I think the scangauge uses :

CarloSW2"

One question, your scangauge works independent from the car ecu?

"the scangauge has a formula that depends on a real IAT temperature."

If your car ecu manage the fuel mixture like the scangauge, could be real mpg values, it depends on how your ecu calc the air/fuel, i don't know how a aftermarket scan gauge work but i thing they probably use the same method as cars