How to add shininess to car textures in Gimp?

[Blighty]

Adding shine and shadows is often more of an art than a technical skill. Many different methods, method will depend on the actual image.

Here is an example of shine (last item - Gimp shiny button):
http://www.littlewebhut.com/gimp/

Here is some info on shadows:
https://www.gimp-forum.net/Thread-Perspe...hadow-help

Will help to post an example image.