I’m hearing people use the phrase “throw under the bus” so frequently that I began wondering about its origin.

Best answer I can find is that the origin is either unknown or unfindable.

Here’s one:

From Slang: the Authoritative Topic-by-Topic Dictionary of American Lingoes from All Walks of Life by Paul Dickson (Pocket Books, New York, 1990), under “Automotive Slang,” “throw under a bus — Sales talk for selling someone a car or van with all the extras and options at full sticker price or better.”

Here’s another from Grant Barrett:

“Despite the Urban Dictionary entry (which, like all such dubious etymologies, lacks details–call letters? station manager name?) I was only able to take it back for certain to 1991, when it appeared in a courtroom context. There is also a bracketed quote from 1984, which, as in HDAS style, means that it’s not certain to perfectly epitomize the term being defined, from the rock-and-roll industry. It has it only as ‘under the bus’ not ‘throw under the bus’ or ‘put under the bus’ (which is a less common variant).”

Anybody else want to weigh in?