Someone on another forum suggests that the singer is Dawn Landes. Listening to other songs on her Myspace webpage, her quirky laid-back style seems the same as in the commercial. There are also a number of tracks on iTunes by her (though NOT "I'm a Believer")
its a female country singer but i cant think of the song
lenka
Erykah badu
Grace Potter
Melanie Amaro
Melanie Amaro
Sounds like Brandi Carlile.
Melody Gardot?
Michael Bolton
Nadine Ackerman Allambie girl
Sophie Milman
Petra Haden