I went to audi.com and sent them an email asking them this same question. They told me that they were the international site based in Germany and so couldn't give me information about American ad campaigns. They referred me to the audiusa.com website. After a couple more emails, they finally contacted again, and this is what they wrote:
'We certainly apologize for the delay in our response we were waiting for information to answer your question.

Our commercial music is composed and arranged for these TV spots and are not available.

If we can help in any other way, please write again.'
Too bad for us. :(
IL
> anybody know the song in the new audi a4 passing commercial?
> i've seen others ask this same question but never seen an answer for it...