Spotify has had its in car device for streaming out for around a year now, when it debuted last April and up until now, you were required to be invited to purchase one from Spotify. However, as of this week Spotify has revealed that now anyone in the US can purchase the Car Thing, without that queue and invite system.
To purchase the Car Thing, you need to be in the US, pay Spotify $89.99 and have a valid Premium subscription. The Car Thing can be used with most modern cars, using an aux jack or Bluetooth for connection. The device connects to your phone for access to your library but makes it more easy to use in the car while moving, hence the large volume dial and accessible media controls.
Purchase the Car Thing from Spotify here.