The “Pioneer Zephyr”, originally known as the “Burlington Zephyr”, was the second streamliner train in the USA to be powered by an internal combustion engine. But unlike the M-10000 of the Union Pacific, power came from a diesel engine, in this case a 660 hp engine from Winton. The set consisted of three cars, the first one being the power car with shovel nose and a mail compartment. The last car was an observation car that offered a lounge with panoramic view. It was built by Budd and delivered to the Burlington Route in early 1934.

One of the most important points in the development were weight savings. So the car bodies were made of unpainted corrugated stainless steel, using new welding techniques. Additionally, the cars were articulated with Jacobs bogies, as it already had been the case with the M-10000. On a publicity run this train managed to cover the 1,015 miles between Denver and Chicago in 13 hours and 5 minutes, with an average of 78 mph or 124 km/h. The top speed attained on this run was 112.5 mph or 181 km/h. Now this train was operated on the line from Kansas City, Missouri to Nebraska via Omaha to Lincoln.

In 1935, the “Mark Twain Zephyr” was built as the second train that was similar to the first one. But this one had three trailer cars and was used from St. Louis, Missouri via Hannibal to Burlington, Iowa. Later there were a total of nine Zephyr trains, but the newer ones had more powerful power cars and more changes. The first two trains were retired in 1960 and 1958. Today the “Pioneer Zephyr” is on display in the Museum of Science & Industry in Chicago. The “Mark Twain Zephyr” was bought by the Wisconsin Great Northern Railroad in 2020. Currently they are rebuilding it with a new EMD 567 engine.