Hi,
I hit my first nebula a day or two ago and yesterday the survey ship that found it started running low on fuel. The fuel usage seemed quite too big considering that the ship was going at about 8% of it's max speed. Then I went to task groups screen and set the speed of the ship to the max speed in the nebula (just by clicking set as both the max speed and current speed already had the correct speed). This dropped the fuel usage to 8%. (screenie from events window:
http://users.tkk.fi/~ametsala/nebula_fuel_bug.PNG)
It seems that the code that calculates fuel usage doesn't use the ships actual speed when the ship's in a nebula.
Couldn'f find anything similar reported but maybe I wasn't looking for the right thing.