What is a "short" in this context?

[Spoons]

In the 1974 movie Phantom of the Paradise, there is a line in the song “Upholstery,” which is about cars, and which says,

“Of all life’s mysteries the greatest one I’ve seen:
My short runs better when it’s clean.”

What is a “short” in this context?

[DPRK]

U.S. slang for a car.

♫ ♬ It happened on the strip where the road is wide /
Two cool shorts standing side-by-side…

[psychonaut]

From the Oxford English Dictionary:

short: U.S. slang. A street-car; a car.

1914 Jackson & Hellyer Vocab. Criminal Slang 76 Short,‥a street car. Derived from the limited extent of a street car ride compared with the distances negotiable by railroad transportation. 1932 Literary Digest 9 Apr. 36 Short, an automobile, used especially in the phrase ‘hot short’, for a stolen car. 1961 ‘D. Shannon’ Ace of Spaces vi. 70 This perfectly good almost brand new Caddy I got for him, a present, an’ he says he can’t handle it‥comes back with this piece of old junk, my God, pickin’ up a thing like—stickin’ me with a hot short to get rid of! 1975 W. McCarthy Fourth Man i. 26 Everybody brings him hot cars‥shorts, we get up north, he fixes 'em up and then sells 'em.