Huh? Outside the northeast corridor, where lots of the facilities are very close to the tracks, for the most part in the US everything adjacent to the tracks is at least 3 feet away from the side of the coach. It is in Europe (and a lot of other parts of the world) that many facilities are very close to the sides of the cars. That being said, it is still a really bad idea to stick your head out while moving at speed. Even a bug in the face at 79 mph will not be a plesant experience. Years ago, I was a frequent stander in the open dutch door person, but htis was mostly in Southern Railway's East Tennessee lines where the curves usually kept the speed in the 40 to 55 mph range. And yes, you did end up with a really dirty face, but I don't recall the diesel fumes as a major part of it. Mostly dust and brake shoe grit. Let's just say I was young and stupid, but even then, I did not really lean out very far. My favorite was really standing in the back vestibule and watching the track unreel behind us. You got just about as dirty, but it was a lot safer.
George