Live for Speed has a great 3D car livery viewer. I believe it is the CMX viewer on
this page.
It requires advanced image editing knowledge to use though, as you must make the artwork in a program like Photoshop then apply it to the car. It is not a user-friendly livery builder like iGP. You will need to get a skin template also from this forum to work
from: https://www.lfs.net/forum/69-Skin-help-tools-templates
There is more help and information available in that forum.