not hating, or anything. but take this from a fellow artist. you need to work on your proportion, shading. and fine outlines. attention to detail is what makes or breaks a drawing.
this is some of my work
this one was a quick sketch
http://c2.ac-images.myspacecdn.com/i...135a4b4a01.jpg
and this is what im currently working on.

been working on this one for a few months, i hardly get any time to do it, but when i do i make little progress because it's detailed and im anal about my work.
Car's are tough, i should probably try it again sometime, this is an R34 i did. my freshmen year. it's poster sized. i believe its around 18" in length.
