Yes, I pressed that reset button after I found out I wasted too much fuel with the combustion engine.
If you decide to keep those obsolete techs in the tech tree, I think you can add the ability to hide certain techs. This prevents too many obsolete techs from cluttering.
If the combustion engine is kept, I think it needs a redesign: Since the fuel efficiency is all what matters, you can increase its base efficiency a lot, but make it not scale proportionally to number of engines. This makes it useful at start, and fusion is still a big improvement.
Alternatively, the real time research speed could be based on proper velocity, so increasing velocity early is still helpful, allowing an early engine to exist.
Another note: When fusion is unlocked, it's relatively easy to research the efficiency curve to high levels. This basically makes that efficiency irrelevant because it's near 100% all the time. This is even more true for antimatter engines. So I think the whole efficiency mechanism should be removed for the fusion and antimatter, and leave it exclusively to combustion engines.