I have modified it so you can use the encoder to move the car left and right (instead of the 2 buttons used in the original code).
The movement feel is not the best, if you move the encoder too fas it won't respond properly. I have tried using the encoder with interruptions (like in www.electrosmash.com/forum/arduino-audio...no-audio-meter-build ) without much success.
The encoder feel takes some time for you to understand it.
Once you pass the first obstacle, it is easier to control