Hello,
news render with keyshot :
(http://img4.hostingpics.net/pics/773427finalpetit.jpg)
http://img4.hostingpics.net/pics/773427finalpetit.jpg
post-prod with photoshop and lightroom !
;)
and step by step post production :
http://youtu.be/A-KOqhYxgQM
The lines at the front end of the car are very much ... horizontal ... which doesn't feel to me as showing nice curved design which is omni-present nowadays in automotive ... no ?
Second the lighting of the car is very .. studio-like ... which doesn't make it blend in the background.
it's cgi image, mix between "studio" and "environment".
i worked on the photo-realistic, ref image : http://www.largus.fr/images/images/Porsche-Cayenne-S-diesel-2012_01.jpg
i d'ont understand your "advice"
I agree that the reference image shows the curve of the bumper and nose a little better, though straight lines are not an issue in itself, it can be an artistic choice. If clear communication of the shape of the car is the goal it might be an issue.