Concept Racer: car sketch process

after reading that concept car thread…

rough sketch, HB on A4 paper, lined with a ballpoint:

coloured it with a neon green highlighter, strangely my scanner took it as pastel?

then scanned the first pencilling and printed it enlarged in lower quality.
traced only the lines i needed and did the shading:

i inked the lines, it seemed to give a nice cartooned feel to it, whereas without the lines it looked very dreamy and vague.

the rendering is turning into an awesome car: for superman! seems to lack a serious look.

its toon avatar is nearly complete now.

but wait! this seems mor serios! photoshopped the hues basically.

in my quest for a realistic rendering, do i take the cartooney block coloured rendering and add shine and reflections? is there any other way?