I really like the product and have never had a single complaint. BUT it is PVC. PVC by nature will stain from hot tires or prolonged exposure to gas and oil. Using Black under the tires is perfect.
Porcelain tiles, other than the potential of being more slick are amazing when properly installed. If you can get a good price and find a good installer, and if you have the need for that level of floor they are pretty sharp.
Picking between those two options for me, I would go with the PVC because I am not the guy that is going to put Porcelain tiles down and I am not going to pay to have it done.
I personally would use a top coat on the PVC tiles. If I am going to invest that money PSF I might as well protect it.