Along with the Union Pacific's M-10000 (which preceded it by a mere six weeks), this pioneer streamliner, Zephyr 9900, would blaze a trail for the many which followed it. It was the first all-stainless-steel train to be built using Budd's patented and proprietary "Shotwelding" techniques. It was also the first diesel-powered streamliner; the M-10000 used a spark-ignition distillate fuel engine. Another notable first: whereas the M-10000 tucked a buffet-kitchen in its rounded and streamlined tail, Zephyr 9900 used the space as a parlor-solarium, creating the first streamlined observation car. (It must be noted, however, that open-platform rear end observation cars had been commonplace during the heavyweight era.)

Following tests on the Reading in Pennsylvania where the little trainset hit a top speed of 104 mph, it was officially unveiled to the press and public at Philadelphia's Broad Street Station on April 18, 1934. But its real introduction to the world came little over a month later; after transiting the Burlington's route with stops at major cities between Chicago and Denver, it was poised to make the run in reverse for a record. As a nationwide radio audience listened in, the Zephyr whistled off from Denver at dawn (5:05 a.m) of May 26, headed for Chicago at top speed. According to the Wikipedia entry for the train, Burlington called in additional manpower to make sure that every single grade crossing between Denver and Chicago was protected by a flagman. The train reached Chicago. 1015.4 miles away, at 7:10 p.m. having averaged nearly 78 mph. From there the little trainset went directly to the Chicago "Century of Progress" World's Fair exhibition, where the waiting crowds went wild.

Following its own nationwide publicity tour, the new Zephyr (named for the Greek god of the west wind) entered revenue service on November 11, 1934 between Lincoln, Omaha and Kansas City. But Burlington already had numerous additional streamliners on order from the Budd company, and they could see that with the Zephyr they had created more than a train—it would be a franchise. Aptly, then, as the additional equipment came on line the original 9900 trainset was renamed the Pioneer Zephyr.

Unlike the M-10000, which lasted less than seven years in revenue service, the Pioneer Zephyr would have a long and productive service life. The trainset would serve the Burlington for more than twenty-five years, finally being retired in early 1960. Even then it avoided the scrapyard fate which awaited most railroad rolling stock; the trainset would be donated to and placed on display by Chicago's Museum of Science and Industry. Following a careful restoration and refurbishment in the late 1990s, it is now possible for anyone to see 1934's "train of the future".