If you need to grind for S-Class freighter upgrades, check out the Derelict Freighter Registry. It even has the Fuel Efficiency and Hyperdrive bonuses listed. All the freighters are in Euclid.
I am not the owner of the registry, just promoting its use. I originally found about in this Reddit post:
Can you do me a favor and edit the subject to have “Resource/Derelict Freighter:” at the start?
Done
Thank you!