Not many car dealerships ever had an airplane in the showroom...

 and since I've already recently covered the Auburn Cord Duesenberg connection with the Stinson, E.L. Cord acquired a sixty percent interest in the Stinson Aircraft Company late in 1929, and none of those are in this photo... and that looks like a Piper or similar tiny airplane smaller than a Stinson

https://www.flickr.com/photos/oklahomahistory/page1