This remarkable Duesenberg is the prototype supercharged Model SJ, used personally by Fred Duesenberg as his experimental and development test vehicle. It represents the very beginning of the supercharged SJ program and stands as one of the most historically significant Model Js in existence.

As Fred Duesenberg pushed the limits of performance and engineering, he used this car extensively for high‑speed testing. Tragically, it was in this very vehicle that Fred suffered a severe accident; he later died from complications related to those injuries. This painful chapter in Duesenberg history is inseparable from the legacy of the car itself, giving it a unique place in the story of the marque.

Mechanically, this example is exceptionally rare. It is one of only eight known Duesenbergs equipped with the special Indianapolis‑style racing manifold, mounted externally along the side of the car, an unmistakable visual and mechanical hallmark of Duesenberg’s racing influence.

Equally significant is the bodywork. This car carries what is believed to be the very first LaGrande Dual‑Cowl Phaeton body ever constructed, marking the debut of one of the most celebrated open-body styles associated with the Model J. Designed under Duesenberg’s in‑house LaGrande styling program, this body would go on to become an icon of prewar American luxury design.