The dining car is usually located in the middle of the train.

car 在这里指"车厢"，特指火车上用于特定功能的独立车厢。dining car 指专门用于餐饮服务的火车车厢，即"餐车"。 car 的本义是"车辆"，在火车相关语境中引申为"车厢"。