One thing that needs doing is to run ships as if they really had fuel to use. If I run 1/4 way to a target and recall the fleet, for any reason, then I've only used HALF the fuel allocated on that trip. I should, therefore, be credited with half the fuel when I get back to base or when I cancel the mission. Returning before hitting 90% of the distance to a target should have some fuel credit.

This is realistic, but it is potentially game breaking. I wouldn't mind it though, means those wasted attacks when targets dodge don't matter so much. It would help the defenders as well, since a player would be more inclined to withdraw, rather than waste the remaining deut damaging the defences at that location (for points or out of annoyance)

Most of the deut would be used upon launch anyways and hardly much when the ships are in flight,
Changing this would indeed increase the odds of a recall,

This suggestion is loosely related to the transport/deploy fuel costs which are strangely the same despite the travel distance... and the non-existing. fuel charge for acs depots
Seems fuel costs are consistently inconsistent across the ze universe,

An interesting, but hard to do idea. This could take weeks, months, maybe more to perfect and implement. Plus, the game mechanics are shaky already, let's not add one more cog to get stuck.