Follow the instuctions in your owners manual as you can't go wrong with that. There is really no need for debate. Avoid sudden starts and stops because the tires and brakes need to be seated in. If you're only going 100 miles, just don't drive at the same speed for the whole distance. Traffic will help you take care of that. I drove 700 miles when I had just 200 miles on my car. I would drive 10 miles or so at 65, then 10 at 70, then 60, etc. It's really only important to just vary the speed somewhat instead of running at any constant speed. You should do this for the first 600-700 miles.
All of the above posts are opinions based on science, mechanics, and some voodoo. Just do what the manufacturer recommends, which is what I have posted above.