> They're almost certainly not storing a static list of numbers.

Probably. But I wouldn't bet on it. I once borrowed a car that would glitch if you pressed the cruise control buttons too fast. Normally + and - buttons increase and decrease the speed by 1 km/h. But if you do it too fast, it sometimes eats the entry, and starts skipping one position. Eg. it would increase from 105 to 107, and decrease from 107 to 105. It was persistent until cruise control was turned entirely off and on again. Eh? Making that bug must have taken more effort than doing it correctly. I guess it must be populating linked lists of possible speeds, and then screwing up the links when clicking too fast? (that was Jeep Renegade)

A lot of the digital cruise controls that I've used in cars increment by 1 for each press, but increment by jumps (3-5 IME) if you hold it down. I wonder if that bug is a state machine problem. Pressing fast enough puts it into the "holding" mode, but because you're not actually holding, it also doesn't register that you've "stopped" holding.