Wiktionary
n. A postmodern genre of art as well as a budding subculture that combines the aesthetics of the interbellum period through World War II and ending circa 1950s (a range of time often referred to as the “diesel era” by the dieselpunk community) with contemporary creations.
Wikipedia
Dieselpunk is a genre similar to that of its more well-known cousin " steampunk" that combines the aesthetics of the diesel-based technology of the interwar period through to the 1950s with retro-futuristic technology and postmodern sensibilities. Coined in 2001 by game designer Lewis Pollak to describe his role-playing game Children of the Sun, the term has since been applied to a variety of visual art, music, motion pictures, fiction, and engineering.