Green’s Dictionary of Slang

hot-rod n.

[hot adj. (2d) + SE piston rod]

1. [1930s+] (US) an aggressive, unruly young man.

2. [1940s+] (also hot iron, hot-up, rod) a car modified for speed and flashiness.

3. attrib. use of sense 2.

4. see rod n. (1)