Reality wrote:After all, it makes no sense to me that someone as strong as Batman would have the same running speed as someone of Rank 0.
On the other hand, there's always the Athletics roll to increase your running speed. It's a DC 15 roll to add +1 to your speed, and Batman's Athletics skill is already +15, so he effectively has Speed 1 available all the time, so he's already twice as fast as most normals and would have the same speed as your house rule would give him without having to customize or recode anything.