View/download from here:
http://www.racesimcentral.net/
The ZIP file contains the Nascar-compatible layered TGA files (both car
and pitcrew) that can be immediately imported to your car. Use
Paintshop Pro 6 or higher if you want to change the car number or other
aspects of the paintjob.
Unzip the files to your nascar4\exports directory and go for it.