Amazon has their Amazon Echo Auto for 29.99 (regularly $49.99) with Free Shipping for a limited time.
The Echo Auto brings Amazon Alexa into your car. Ask Alexa to play music, continue your Audible audiobook, check your calendar, find nearby businesses, or make calls. With 8 microphones, Echo Auto even hears you over road noise. Echo Auto starts up in seconds, works through your car speakers, and pairs with your existing smartphone plan.