I am going in the next couple days to order a Laramie Eco. In searching the forums I can't find anyone with good MPG numbers towing. I am going to be towing a 4000lb trailer about 90% of the time for the life of the truck mostly flat freeway miles. I am hoping for 20mpg at least, as I am getting 13MPG in my current vehicle. Anyone have any similar setup to share?