Originally I planed to use a wireless bluetooth link, it explains why I started and kept an ESP32. It's a bit overkill for the task, but there is nice libraries for plenty of devices. I used Platform.io on Visual Studio Code, with Arduino, for the development.

One interesting point here is the use of the 3 serial ports. One for the programming / debug, one to the ELM327, and one to the LCD screen.

I also add a little Oled display for debug and showing what speed is acquired.