On the highways here, you can regularly cruise at 85-90 with no issues and as Pete alluded to, dawn patrols even more. I used to commute from So San Jose to Marin county (yea, it was a good job) and I was completely floored at the commuters on 280 at 6am. 10-20 car groups hitting 110-120 for 5-10 mile stretches. Crazy fun but I had to borrow the girlfriends BMW as my Jeep Wrangler and the prerequisite soft top, would beat me to death at anything approaching 80 mph.
Can the Jag cruise at 90-95 mph with a 3.08 for extended periods of time (assuming everything is in good running order)??