You wrote it like „diesel trees” would be working in a way where you simply chop it down and put it in your gas tank.
Making and then using „diesel trees” would definitely require special equipment and manufacturing pipelines that might be the same cost or more than those for solar panels.
It's my science fiction story, so I'm going to say the tree we engineered for this was the sugar maple: you can put a tap in it and collect highly pure diesel fuel with a pre-Columbian level of technology.
Making and then using „diesel trees” would definitely require special equipment and manufacturing pipelines that might be the same cost or more than those for solar panels.