That's likely already online because Europeans have had Spotify in their car for awhile now, due to Rdio's demise.
I would tend to agree. However the link that @SouthlakeDad shows the URL as "support.spotify.com/us/using_spotify/play_on_stereo_tv_car/tesla/....." The "US" in there signifies that it is the USA version of the site. Whereas the European versions contain UK, DK, DE, FR, etc instead of US.
Therefore I would say that link shows us the Spotify is finally coming!
Thanks Erik