Green’s Dictionary of Slang

buzzer n.2

[the noise it makes]

any form of automobile.

[UK] (ref. to 1898+) in J. Ware Passing Eng. of the Victorian Era.
Hopsville Kentuckian (KY) 30 Nov. 3/2: His 60-H buzzer was there with the goods, / Her engine was working as sweet as ice cream.