Vehicle utilization report

I would like to see additional reports on vehicle utilization.
Specifically, I would like the load * distance to be tracked, and I would like be able to see this information by vehicle group. (e.g. unassigned only, vehicles assigned to specific building, etc.)
I periodically find the trucks getting _*very*_ busy. Unfortunately, when they do, it can be difficult to determine why. With this information, I could see where they are spending the most time.