Originally named "Classical Gasoline", the song was envisioned to be "fuel" for the classical guitar repertoire. The title was later shortened by a music copyist.
Williams was the head writer for The Smothers Brothers Comedy Hour at the time of the piece's release and premiered the composition on the show. Williams performed it several times over several episodes. After the piece had reached the Top Ten, Williams asked an experimental filmmaker named Dan McLaughlin to adjust a student video montage that he had created of classical art works using Beethoven's 5th Symphony and edit it in time to "Classical Gas", using the visual effect now known as kinestasis. The work, 3000 Years of Art, premiered in 1968 on the Smothers Brothers.
The song peaked at number 2 for two weeks in August that year. On the US Easy Listening chart it went to number one for three weeks.
Williams re-recorded "Classical Gas" as a solo guitar piece on his 1970 album Handmade. This version was re-released by Sony in 2003, after being featured in the film Cheaper by the Dozen (which starred Williams's Smothers Brothers protégé,Steve Martin).
There is a common misconception that "Classical Gas" was composed and originally performed by Eric Clapton. Clapton has never recorded a cover of the song. This misconception may possibly be attributed to the fact that Clapton was musical director of, and played much of the guitar music for, the feature film The Story of Us. The version of the song on the film's soundtrack is actually Williams' own solo-guitar re-recording of it, from his 1970 album Handmade.
In 1998, Broadcast Music Incorporated (BMI) awarded Williams a special Citation of Achievement. The piece has logged over five million broadcast performances to become BMI's all-time number-one instrumental composition for radio air play.