Eventually I discovered that whenever I got out of my car the passenger door would pop open. It was a quirk, and not the last my car would contract. At one point slamming my trunk shut would make the horn honk, a noise that startled me every time it happened. Diagnosing and curing quirks is handled with a fun minigame in the garage using a terminal to pick words from four columns to form if/then statements, such as SHIFTER / IS IN DRIVE (the cause of the quirk) so HOOD / OPENS (the quirk itself). If you diagnose your quirk correctly, the computer tells you what you need to craft to fix it.