racer n.

"one who or that which races," 1640s of persons, 1660s of horses, 1793 of vehicles, by 1809 in American English in reference to a type of snake; agent nouns from race (v.).

WHEN a lad, I lived with my father in the then province of New Jersey, where the black snake, with a white throat, commonly called the racer, as well as the rattle snake, and other serpents, are frequently met with ; and I never remember to have heard any one dispute the power of charming belonging to several species of serpents, but more common to the black snake, called the racer, which I have twice seen in the operation. ["Extract from a letter from Samuel Beach, dated Whiting, July 24, 1795," in appendix to Samuel Williams, "The Natural and Civil History of Vermont," 2nd ed., 1809]