Wikipedia
The French word Autorail describes a single powered railcar capable of carrying passengers. While the concept faded for a while, it has been introduced with a new range of vehicles for both standard and metre gauge lines.
Many autorails from the 1950s and 1960s form the basic transport of many French preserved railways, of Chemin de Fer Touristique (sometimes Historique). They can be used at times of year when steam locos might cause fires. They have quick availability and do not require the specialized infrastructure needs of steam locomotives. Many lines have both steam and diesel traction, however, steam is often reserved for peak periods and weekends. The power of these machines allows them to pull a small number of trailers if passenger loads necessitate.
Usage examples of "autorail".
Mlle Germaine took the autorail and was met at the station by the police.