First I have never heard of a heated windshield. Till now. But that would be sweet. So I stand corrected on that one. But, a gallon of diesel is a steep bet but I'm willing to take that bet. Because last winter my mirrors iced over many a times and they never melted. My brother, dad, and brother-in-law all own 08's too and they all have a button to turn the mirror on. The window defost is on a knob. They are not XLs but we just never opted for the fancy "doo-dads." WE are too redneck for that. Our version of climate control is roll the window up or down. And, the button has a picture of a mirror on it. Like Dave said, the 07 and older models are always on. I have no idea about that, but i know in all of our trucks, they are not on unless you turn them on.