Yup, we set out for this purpose. To get a good time. Though we were aiming at 13-14 hours max. As mentioned, it was the second day of Eid ul Fitr, so very little traffic. And also the roads were in very impressive condition, except for this one bad patch just before Multan (if my memory serves me right) - I heard from a friend who used the N5 soon after, that there was a lot of road work going on, hence diversions and speed breaks - we didn't face that. We were in a Civic. And it is to be noted that we didn't even stop to eat on this stretch, home made kebab rolls were carried when leaving from Karachi Lol.
Good luck
And the time quoted is true. I'm actually surprised that nobody here has quoted the same time, or better for that matter.
Oh, there you go 