"My Best Friend's Girl" is a song by American rock band the Cars from their 1978 self-titled debut album on Elektra Records, released on June 6 of that year.

Written by Ocasek as a song about something that "probably ... happened to a lot of people," the track found radio success as a demo in 1977.

Written by Ric Ocasek and produced by Roy Thomas Baker, the song was released as the album's second single.

[3] DJ Maxanne Sartori, who was given the tapes of these songs by Ric Ocasek, recalled, "I began playing the demos of 'Just What I Needed' and 'My Best Friend's Girl' in March during my weekday slot, from 2 to 6 p.m. Calls poured in with positive comments.

[5] "My Best Friend's Girl" begins with chords in the lower register of the guitar, a two-bar progression moving from I to IV to V in F.[6] Hand claps enter in bar five, and after the eight-bar intro (following descending synthesizer sounds from David Robinson's Syndrums,) the first verse begins featuring Ric Ocasek's vocals over a lead guitar lick in the key of F.[6] An electronic piano (a Yamaha CP-30) is introduced in the first chorus, followed by a rockabilly guitar lick which leads to the second verse.

[16] Cash Box said that "the guitar work is derivative but the enthusiasm is refreshing" and praised the vocals and organ playing.

[citation needed] Some critics have noted the similarity in style of Fountains of Wayne's 2003 hit single "Stacy's Mom" to this song.