You can get Alexa in your car with Echo Auto, but there are a bunch of other ways, including that extra Dot you might have laying around.
How to get Alexa in your car with this amazing new gadget
How to Get Alexa in Your Car
Alexa in Your Vehicle - Enrich every drive with Alexa
How to add Alexa to your car for less than £15 and save £100s of pounds
Want Alexa in Your Car? How to Set Up and Use 's Echo Auto
Complete Guide to Integrating Alexa Into Your Car - AskMen
Echo Auto: Now, you can bring Alexa into your car
Alexa, where's my car?' Automatic syncs your vehicle with Echo - CNET
How to get Alexa in your car (DIY Smart Car)
Echo Auto - Add Alexa to Your Car