Everyone always throws up the BS flag on me but I swear on the life of my first born that I kept up with an '04 Supercharged Saleen Mustang in a 60-120mph run. By the end my car was still on his rear bumper when he shut it down for a bend. This is in a non-S 2.7 Boxster. They might not be the fastest at the strip but once they are moving, they're fast at high speeds.
BTW: Clear straight freeway, no cars ahead (drive safely).