here i am again :rant:

First of all your model looks(in my opinion)a little to smooth, second of all look at your refference foto's you will see that on the bottom the shape will go a little inward creating a little rounded out shape instead of the box like shape .
third; give the grill a specularcolor (if you haven't already)and turn of all other colors.
- i think that your glass only needs refraction==>under the raytrace tab set it to about 1.4.

i really like your tire/rim though

i've added a picture below to clearify

good luck

edit: the lines are the places that need more definition especially the mirror it's not that smooth there is an arched line there.
you should move forward where the sideviewmirrorhandle meets the actual sideviewmirror .