[AgentZero]

I could see how an emergency slow/fast toggle might be a bit interesting. Emergency slow would cause your ship(s) to move at 1/2 speed, so a ship that normally had 8 moves would have 4, but the advantage is that you only use 1/4 the supplies. Might be a good for long range scout ships.
Emergency speed on the other hand would give you 50% more movement, so our 8 move ship would then have 12, but it would use double the supplies & run the risk of damaging or destroying engines. But it'd sure be helpful if you needed to get ships to the defence of another planet that was about to be attacked & said planet was just outside your normal range.