Paul Gerding (1895-1983) made a number of very nice illustrations for automobile advertisements, especially in the late 1920s to mid-1930s. He did other work, but I found little of it on Internet searches. Part of my problem is that illustrators did not always sign their work -- usually due to the ad agency or its client's policy.
Because of all that, I could find little more than Gerding's birth/death years. So this post simply focuses on the examples of his work I selected.
The image above is cropped from a 1932 Pierce-Arrow advertisement. Pierce-Arrow was a luxury brand in decline due to the Great Depression and strong competition from the likes of Packard and Cadillac. I think Gerding did a fine job here, especially the lighting and use of color. Media were probably watercolor and gouache.