Two same ships, the only difference is “Standard STL aka SE” vs “Fuel efficient STL aka FE” engines. Since there are no visible parameters/specs for engines. The description says (FE) less power full, better economy, also lower “acceleration max”
Simulation Vallis to Moria station.
FE
SE
It is weird that SE is 4 hours slower than “less powerful” FE…with slight fuel saving. Also there is almost zero difference among engines.