Hi,
I found the following on wikipedia:
Mustang Sally is a rhythm and blues song written and performed by Mack Rice and best known through a cover by Wilson Pickett.
According to music historian, Tom Shannon, Mack started the song as a joke in 1965 when Della Reese's band leader wanted a new Ford Mustang. Mack called the early version "Mustang Mama," but changed it after Aretha Franklin suggested "Mustang Sally".
Rice's version made it to #15 on the R&B Charts. Pickett's version made it to #23 in 1966.
The song was featured in the film The Commitments (film), and has been covered many times, including by Los Lobos, The Young Rascals, Eric Clapton, Hootie and the Blowfish, Silver Apples, Rufus Thomas, Joe Cocker, Delbert McClinton, and Buddy Guy.