The best looking ones I ever saw are from Orb on his Porsche Carrera GT. There was a thread on CGCars, not sure if it's still there. Some pics a bit of googling gave me :
http://i160.photobucket.com/albums/t...-Interior3.jpg
http://i160.photobucket.com/albums/t...-Interior2.jpg
http://i160.photobucket.com/albums/t...T-Interior.jpg
Just don't look on stitches on foreground, the depth of field effect is ruining them. Maybe you can try to reach to ask for informations, I think he will help you. I really don't know / don't remember how he did them.
I also saw (here I think) fully modeled stitches, it's like fully modeling a tire sidewall : it take loooooong !