Hey everyone, For anyone considering buying a 6.0L Vortec 2500HD, I just got home from the Candian border (Blaine, WA) and took I-5 to Edmonds, WA. When I filled up in Edmonds, I used 5.4 gallons to go 90.2 miles. which works out to about 16.7 MPG. I was happy with this number. Hope this helps for anyone wondering.