Green’s Dictionary of Slang

(US) an automobile.

1915		G. Bronson-Howard God’s Man 198: Who wouldn’t, with a little ten-thousand-dollar go-cart sent around every afternoon to ride her around again, Willie.
1943		R.L. Bellem ‘Phoney Shakedown’ Dan Turner - Hollywood Detective Feb. 🌐 I [...] hurled myself at Lew Sultan’s gaudy go-cart.
1961		R.A. Heinlein Stranger in a Strange Land 145: Get your go-cart out of my flower beds at once or I’ll make a civil-rights case out of this.