Occasionally this rule will bite you (ok, rarely, but it does happen) when you want to spend your last point on a sN or sD and remain in motion comfy in your smoke cover. Then you fail the smoke attempt and don't want to stop, or spin, or move to the next open ground hex, but you have to do something.
So Doug, (and Craig), this extra 1 MP is not such a big problem usually....
If you go back to:
"D2.4 MOTION STATUS: Any Mobile vehicle (including a boat or amphibian) which has used its entire printed MP allotment during its MPh, without expending a MP to Stop (2.13) or Delay (2.17) at the end of that MPh, is considered in Motion and covered with a Motion counter. A vehicle may end its MPh in Motion without expending all of its MP only if it has insufficient MP remaining to enter the next hex it wishes to enter." ...
So... if you are bypassing a hexside of a building with only 1 MP left, and therefore do not have enough to make the turn to the next hexside, you end your MPh in motion in that hex. The extra MP is expended in that hex per D2.1.
I will say that D2.1 does throw a little confusion on the "vehicle must expend all its MP" concept when it opens with, "2.1 A vehicle may expend up to its full MP allotment..."
"may"?
Just another one of those things that makes the ASL Rules so much fun!
JT