No, I'm working with PS. I tried Gimp at first, but there was no polygonal lasso tool that I could find so I quickly switched to PS. I've actually written a tutorial myself on my technique of motion blurring, which seems to be slightly different from most people's. Works well for me though.
In other news, that Nismo picture looks great. Very little color, gives it a lonely, almost ghostly feeling. I like it, very clean.