i have it on my 2500hd high country, i like it in the winter, helps engine warm up quicker, so you really dont need a engine cover for the winter, when it is come to MPG nothing, worthless on the gas trucks but every gm trucks comes with it standart, a lots of trucks missing shutters but nobody complains about it and no credit paid to the buyers, you just have to pay attantion when you buy anything new .