There are new technologies which will reduce fuel consumption

For terrans - by types of engines.
Optimization of the Rocket Engine
Optimization of the Impulse Drive
Optimization of the Hyperspace Drive

The evolution of consumption for xerjs was enhanced from 1% to 1.5% and the negative effect of amortization was removed.

Technologies for tosses were added according to the type of ships: civil / battle.
Fuel Processing of C-engines
Fuel Processing of B-engines

If you do not see the new technologies probably requirements for them have not been met yet. Requirements can be found in the "Technology tree"