McKeen Motor Car at the Southern Pacific Depot, Strathmore, California. Image taken 1911-1913. The motor car shown here was a US Mail Railway Post Office.
They were the first successful gasoline train cars, and were made from 1905 to 1917, while 152 were built, only three still exist, with one completely restored at the Nevada State Railroad Museum
One of their major failings was lack of a reverse gear. In order to back one up, the motor had to be stopped, the camshaft set to the reverse position, then the engine was restarted in reverse.
www.mckeencar.com found on https://www.facebook.com/pages/Antique-Images-from-the-Collection-of-Michael-J-Semas/319722608043803?fref=photo
Southern Pacific Mckeen Motor Car Number 45 Sacramento California, 1931.
Found on https://www.facebook.com/HeritageRailway?fref=photo