When I got my Pantera twelve years ago the carpets were in good shape but were faded and had a slight brown tinge in the areas that received the most sunlight. The fading was mostly along carpet covering the inside rocker panels and the area beside the console. Because the carpets were in good shape it didn't make a lot of sense to buy new ones, so I dyed them using vinyl dye paint. After twelve years of southeast sun exposure they started to fade again, so it was time to do some touch up.
View of the completed process along the carpet covering inside rocker and wheel well. The carpet piece with the de Tomaso logo is a floor mat sold by Pantera Performance. .
I used Dupli-Color Vinyl and Fabric dye. The dye works best if you vacuum the carpet real well and then use a number of light coats. Let the carpet dry between coats and re-vacuumed to lift the knap.
I used a file folder to protect the areas that I didn't want dyed.
I've only used the black color but I expect the gray dye would work well too. Dupli-Color makes a number of gray shades.