Motor cars. Railroad motor cars lovingly restored and maintained by people who love one particular aspect of railroad history. What an amazing hobby.
And what a great way to spend a summer day in the Upper Peninsula, cruising along the (at that time) Wisconsin Central tracks. I'm not sure just how many miles they were allowed to use that day, but they started over towards Marquette, drove to Baraga, and then drove back again. Photo below is the back end of the parade as they head up the grade to Summit. It's a 10 mile continuous uphill grade with a number of long stretches at 3%, which makes it, for a railroad, quite a hill. It's one reason trains always go through our place really, really slowly, regardless of direction.
I'm not sure just when the railroads stopped using specialized motor cars and switched to pick-up trucks modified for use on either pavement or rail. The Old Man retired around 1983, and was using a truck the last year or so that he worked. From the viewpoint of the workers, the trucks were a huge improvement. (Among other things, it's a heck of a lot warmer in a pickup in January than it is in an unheated motor car with canvas sides.)
Below is a early '50s photo of the same stretch of track shown above right about at the point where that last motor car is: