Feedback
I had gotten the idea of using the mirror modifier from this video, as creating a 3D character would provide troubles if the character needed to be symmetrical. From this tutorial, I had been able to implement this idea into my 3D car model.
Video
I asked my design friend for feedback on my window. This is what he said:
Pros:
Clean low-poly style.
Good overall SUV/wagon silhouette.
Door proportions look natural.
Body crease adds visual interest.
Could Improve:
Make the window pillars (especially the B-pillar) a bit thicker.
Add a slight curve to the roof instead of it being perfectly flat.
The windshield-to-hood transition feels a little sharp.