Green’s Dictionary of Slang

a person who drives or races a car that has been modified for speed and style.

1947		Van Nuys (CA) News 20 Nov. 1/5: [heading] Hot Rodder Up for Sentence on Dec. 11.
1959		E. De Roo Go, Man, Go! 76: I’m Gene Kuppel of the National Hot Rod Association. You look like a hot-rodder. Member of the Speed Demons, are ya?
1967		N. Mailer Why Are We in Vietnam? (1970) 9: Hot rodders, hunters, cattlemen, oil riggers [...] and insurance finks.
1975		H. Ellison ‘Along the Scenic Route’ in Deathbird Stories (1978) 42: You’re no hot-rodder, George. You’re a family man, and this is a family car! [Ibid.] 43: It was a standard trick used by rods to rattle their opponents?
1986		S. King It (1987) 344: The other was this smashed up hotrodder.