After reserching the internet on auto carpet dying I dyed the faded carpet in my 71 R/T Challenger with this stuff I bought at my local Advanced Auto.
http://www.duplicolor.com/products/vinylFabricCoating/


I was extremely happy with the results.

I don't have an after pic yet but my carpet was in very nice shape, just faded for the western heat as shown in the pic.

No odor, color of carpet is very consistant.

I think I used 2 1/2 cans as I did the front and back carpets with multiple coats on them, the carpets looks like new now.