The autosell is actually good, it just sells 100% of energy overflow. The autobuys are ineffective, though, probably even after you unlock the ability to stop them if they are unprofitable (you should have this research done already).
Viewing post in Light the City! jam comments
Then I don't understand anything. I tought the aotobuys we're perfect, so if I buy manually is cheaper? I didn't see that anywhere.
And the autosell is only 100% with and engineer right? I can't spare and engineer for that, I only have 3, I need one to buy coal, one to buy oil and one for research. So I need to sell manually.
No, autobuys are perfect, they have no running costs - but you as a player can generally buy a lot of something when the price is low and live with that, and that is more effective cost-wise.
If you have 3 engineers, you can automate autosell and have everything running well, if you decide to drop coal or oil. Save the one that gives the most profits; the rise of selling efficiency to 100% should be well worth the drop.