There’s another thread about “reliability” that’s worth a browse:
https://clubjazz.org/forum/index.php?topic=9589.0Some comments in there about what we mean by “reliability”, eg some contributors felt that only defects that actually immobilised a car would be reason enough to call the car unreliable. Some surveys use data from warranty companies, ie if an owner has felt strongly enough about something to get it fixed under warranty then that gets factored into some quantitative measure of “reliability” (doesn’t work for manufacturer’s warranties though, they don’t publish that data, nor for defects that aren’t covered by the warranty).
Personally I think there’s a missing piece of the puzzle, which is the methodology for translating a list of defects into a measure of reliability. That would involve making assumptions about the severity of any defect, whether it affected safety, performance, environment, and any number of other things. That’s going to be very subjective. It’s probably possible to base something around your drug analogy but I doubt there’s a universally-agreed way of doing that.
Regarding your TPMS issue, it’s undoubtedly annoying for you and I wouldn’t belittle that. But it only occurs intermittently, it doesn’t prevent you driving the car (after manually checking the tyres, of course), and it can be reset easily. Should that brand the car as “unreliable” ?