Green’s Dictionary of Slang

1. (Aus./US) a horse.

1917		Van Loan ‘Eliphaz, Late Fairfax’ in Old Man Curry 153: An argument to excuse yourself for shipping that [...] hay burner around the country.
1926		S. Young Encaustics 2: You don’t know what’s on, whether he’ll swack or not, and whether he’ll bring a son-chariot or a hay-burner—. [Ibid.] 4: You’d know a hay-burner was a horse.
1929		Queensland Figaro (Brisbane) 1 June 5/2: Back in the days of the hay burners, if one family on the street got a horse, all the rest of them didn’t think they had to have one too.
1932		Referee (Sydney) 26 Oct. 3/1: The longest odds I have seen quoted on a horse in years were 1000 to 1 against a hay-burner named Simple Singer in a claiming race at Belmont.
1940		J.H. O’Hara Pal Joey 39: Time is getting short Charley says before the hay-burners stop running at Hialeah.
1946		W.L. Gresham Nightmare Alley (1947) 259: I’ve got to get the roll down on that hay-burner in the third.
1962		Ragen & Finston World’s Toughest Prison 803: hay burner – A horse.
1967		J. Wynnum I’m a Jack, All Right 90: He got off, led his horse through [the gate] [...] when the hay-burner gave a buit of a whinny and dropped down dead.
1969		W. Moxham Apprentice (1991) 31: ‘I reckon His Honour has three hay-burners in work. No hope of paying for their feed far as I can see’.
1978		J. Dingwall Sun. Too Far Away 93: Come on you bloody hayburner, come on!
1983		R. Baker Growing Up 72: Barney Google was a comic strip character and Sparkplug was his racehorse, a stolid square-cut hay burner to whom Barney was devoted.
1984		S. Thorne Battler 69: In partnership, Dan and Big Arthur had owned a succession of ‘chasehorses’ (horses that usually chased the field) and much of the profits from their various ‘sidelines’ was lost on these hayburners.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 29: However, his intrepidness with the bookies was not matched by his choice of winning-type hayburners.
1998		J. James et al. People and the Earth 52: Before the invention of planes, cars, and buses, the preferred way to travel was a ‘hay burner’.

2. a cheap automobile.

[1900		N.C. Green Story of the Galveston Flood 173: The track was so covered with mud and grass that it was exceedingly difficult for the ‘hay-burner’ motor to propel the car].
1921		DN V 114: hay-burner, n. [...] 3. A cheap automobile.

3. (US) a Western film.

1948

W. Tucker Dove 35: ‘What is a hay-burner?’ Elizabeth interrupted. ‘A horse opera,’ Horne provided. ‘An oater, a Western.’ [DA].