From prohibition-era moonshiners to the 2000s MTV classic Pimp My Ride, people have repairing, upgrading, and modifying their cars for a long time. More recently, low-cost microcontrollers like the Arduino have opened new doors for makers looking to do fun and interesting things with their vehicles.
Projects covered here are:
Speed display for your windshield
Turn signals upgrade
Remote start using a laptop or smartphone
Parking assistance
Colored interior lighting with Bluetooth-controlled LEDs
See https://opensource.com/article/17/5/upgrade-your-car-these-5-arduino-projects 
5 Arduino projects to upgrade your car
The Arduino microcontroller opens new doors for auto hobbyists and tinkerers.