Nice renders, I'm looking forward to see more progress on details for this baby.
I'm not sure with the diameter of your muffler tips, they look too large IMHO. The Mustang badge at the front looks too thick. Not in terms of depth but in terms of width of the surrounding part.
Are you modeling the same version than this refpic ?
http://www.madness-us-cars.com/fonds...coupe-1964.jpg
If so, I think you have some accuracy issues. Let me know if I posted a wrong refpic, otherwise I will spot every single problem I've seen.