Having never owned a truck with an avg economy computer, (DIC) it has proven enlightening. While accuracy is sometimes not the greatest, and is really thrown off with many tuners/modules, it DOES give pretty good indication of what happens when you blast past csomeone or let the truck idle, or even drive off cold and the trans is in cold shift mode etc..

In order to get decent mpg you need to excercise restraint when passing, and minimize cold engine and idle operating time.