Oil also loses quite a bit during refining and transport.
And so on.
P.S. Since I drive a stick, I coast a lot. I live in a hilly area, and have a pretty good feel for just how and where I can shift into neutral and coast. I also coast towards a red light with the goal of reaching the intersection just when it turns green. (Moving forward from a dead stop uses lots of energy.)
Anything with electronic fueling will cut fuel during engine overrun. Staying in gear while coasting uses zero fuel. If you pull the clutch, the engine has to fuel enough to idle instead, which is actually a really inefficient fueling regime.