These are always some of my favorite shots, as I have taken way too many of them. However, this really doesn't give me a feeling of looking through a window at a subject. The composition and exposure are near flawless, but it really doesn't meet the challenge in my opinion.
Shots of side-mirrors always feel like a cop-out to me and are the hallmark of the beginner photographer. It communicates that the photographer couldn't be bothered to get out and take a really good photo. Nice sky though.
Where is the frame? Mirror are not window are they? But also this "frame" is not much interestin and not eather the subject so maybe step out of the car next time ;)