Maybe think about putting diesel in the game.
Come on man, this is literally the single most requested thing on these forums. It has been discussed many times, so please, use the search function next time you have a question or suggestion.
Fixed
It would be cool if we had options for fuel lines and fuel pump upgrades.
There is no real interesting design choices to be made for either of those things in my opinion
There is no real interesting design choices to be made for either of those things in my opinion[/quote]
I also do believe that the theoretical quality of fuel-pumps and etc is governed by the tech pool for fuel systems anyway, correct, Daffy? 
Not Daffy, but yes, you are correct 
upping quality does give you various benefits, which come from all fuel-system related aspects.