Reading this answer I realized that for my purposes I don't really want a fully steampunk world. All I want is lack of cars and planes as we know them, and lack of oil, or inaccessible deposits of oil, would work like a charm. Still, I do need access to coal for my world, mainly to have steel industry, but also heating in winter and other little things like that.
What is the smallest change to Earth's geological history and traits to have crude oil unavailable, and coal accessible and as cheap as it was? It does not have to be black coal as long as it's energetic enough for steel production. Or is that totally impossible?
Linked answer and my attempts at research suggests it would be hard / impossible, but I hope you know something I wasn't able to find.
Note: I know it is not that simple not to have cars, and I know early internal combustion engines used wood gas and coal gas. I know we can convert wood and coal into gasoline, or close enough to power modern engines. No problem, I can work with that if only I can get rid of petroleum. It might be a topic of follow-up questions, for now don't bother, please.