If nobody else, Clessie Cummins had proved to Americans the viability of the diesel engine. Familiar with the Indianapolis 500 since crewing for Ray Harroun in the first such race in 1911, he returned in 1931 with a Duesenberg-built, diesel-powered race car that finished 13th, but managed to not only run the entire race without pitting (averaging 16 MPG), but also be driven to the track and back.
The fuel economy that the Cummins engine exhibited at Indy managed to attract the interest of truckers; the next year, Kenworth became the first truck builder to offer diesels as an optional engine. Yet automakers still believed the diesel engine was too heavy for passenger car use. Clessie Cummins set out to change that perception.
In June 1935, he debuted the result of that effort: a 1934 Auburn powered by an experimental Cummins Model A six-cylinder diesel. Where all of Cummins’s previous diesels used cast-iron engine assemblies, the Model A had an aluminum block and head, “making it more comparable in weight to a gasoline engine,” according to Cummins company literature. A Time article announcing the Cummins-powered Auburn noted that the Model A, which developed 85 horsepower from 377 cubic inches, weighed 80 pounds more than the Lycoming straight-eight that originally powered the Auburn (870 pounds total). Combined with a three-speed manual transmission and a two-speed rear axle, the 4,000-pound car was able to pull down 40.1 MPG on the first leg of a NY-to-LA transcontinental trip that Clessie planned to display the economy of the Model A engine. The trip, which lasted from June 17 to July 4, covered 3,774 miles and consumed just $7.63 worth of fuel; assuming the same fuel cost quoted in the Time article (and assuming my math is correct), that translates to an average of 44.5 MPG over the entire trip.
Cummins very nearly succeeded in entering automobile production with the Model A. According to Jim Donnelly’s profile on Clessie Cummins from HCC #62, November 2009, E.L. Cord asked Cummins to build three diesel-powered 1935 Auburn airport limousines. Cummins did, and one even appeared on a stand at the 1936 New York Auto Show, generating rumors that Auburn would soon offer diesels across its product line (and that Ford and Chrysler were right on Auburn’s heels). Yet Cummins couldn’t help but see that Cord and his empire couldn’t sustain production of gasoline-powered automobiles, let alone diesel-powered cars, for much longer, prompting Clessie Cummins to sever his relationship with Cord and Auburn.
The Auburns weren’t his first attempt at a diesel-powered automobile – he famously kept his company from going under in the early days of the Depression by fitting one of his Model U engines to a mid-Twenties Packard and exhibiting it at the 1930 New York Auto Show. Nor were they his last – he apparently also dropped one of his diesels into a 1938 Cadillac. Yet, had the Auburn venture panned out, Cummins and Cord could have laid claim to offering the first production diesel-powered passenger cars before Mercedes did so in 1936 with the 260D.
As for the four Auburns, one – Clessie Cummins’s personal car – still exists in the collection of Cummins. The company undertook a restoration of the car in 1974 and today displays it in its headquarters in Columbus, Indiana.
(Thanks to Michael Owen of Cummins for the pictures of the diesel-powered Auburn on display in the company’s headquarters.)