Such model would promote turtling (which might be good or bad, depends),

Not really, since you're always in shortage of fuel (because of say, domestic consumption alone) you're always on the lookout for new planets. You move scouts and find planets, then colonize them, and concentrate force to defend them but that's hardly turtling.
Also, you can balance shortage of other minerals so that its relatively easy to build a weak ship, but incentivize users to save up and build stronger warships.

Regarding WWII:
http://vanrcook.trip...uelshortage.htm

Interesting insight into WWI cause and effects and even Iraq as conflicts motivated by scarceness of fuel wouldn't you agree?

Such model would promote turtling (which might be good or bad, depends),

Not really, since you're always in shortage of fuel (because of say, domestic consumption alone) you're always on the lookout for new planets. You move scouts and find planets, then colonize them, and concentrate force to defend them but that's hardly turtling.
Also, you can balance shortage of other minerals so that its relatively easy to build a weak ship, but incentivize users to save up and build stronger warships.

Regarding WWII:
http://vanrcook.tripod.com/Germanfuelshortage.htm

Such model would promote turtling (which might be good or bad, depends),

Not really, since you're always in shortage of fuel (because of say, domestic consumption alone) you're always on the lookout for new planets. You move scouts and find planets, then colonize them, and concentrate force to defend them but that's hardly turtling.
Also, you can balance shortage of other minerals so that its relatively easy to build a weak ship, but incentivize users to save up and build stronger warships.