Oops, my mistake. PHL is correct, the BC car is at the front, right behind the engine. I forgot that Amtrak made that switch back in April. The Quiet Car is now always the last car on a Regional train, it used to be right behind the engine.

Acela's however are all over the map, there is no predicting where the First Class car will be. I've seen them at the front in NY, DC, and Boston. I've also seem them on the rear in all those locations. It varies since trains that start/originate in NY often go around the Sunnyside loop, so one can never predict it.

The quiet car however is now always the car closest to the First Class car on an Acela.