Hi, How accurate is the MPG reading on the DIC. The best I'm getting out my truck is 13.0 MPG. My wife has a 2500HD 4x4 crew cab with 8 ft bad. She is getting 13.2 MPG. Argh! She also tows a 5th wheel/goose with three horses almost every weekend about 25 miles. Should I expect more than 13.0 MPG?