Figured it was high time for some good ole fashion sketching... Hadn't done a car in awhile so here it is. I followed the ID Sketching tutorial closely but I used a rough sketch from my sketchbook as an underlay instead. I find that I work faster on paper/scanning. I think it is because I use a tablet and not a Cintiq. Originally I didn't think there was a disconnect but the more experience I get, the more clear it becomes.
I would watch the ID Sketching video for the step by step, but there is one gem of knowledge that might help you get the color I achieved quickly. When I finished all the layers were greyscale. I flattened the entire file in photoshop. Next, I colorized it using hue/saturation (hotkey ctrl+u) and selected my color. So the whole image is colored. Use the Sponge tool (in the dodge/burn palette) to remove the areas of color you don't want i.e tires background etc. BAM done.