Amazon has Roav Viva by Anker, Alexa-Enabled 2-Port USB Car Charger in-Car Navigation, Compatible with Android and iOS Smart for $14.40. MSRP $35.99 - 60% off.
It is exactly Echo Dot along with two USB ports for charging in Car Cigarette lighter port.
Alexa Inside: Amazon's voice service gives you complete voice control in your car. Just say the word to get directions, listen to audiobooks from Audible, shop online, play music, and more over Bluetooth, Carplay, or Android Auto. (Note: FM transmission, AUX, and Spotify are not supported.)
High-Speed Charging: Dual charging ports equipped with Anker's exclusive PowerIQ technology deliver blazing charging speeds to both driver and passenger. Qualcomm Quick Charge not supported.
Supports Alexa Communication: Calling, Messaging, Drop In, and Announcements—all hands-free.