Comment Re:I have an even better idea (Score 1) 304
Most cars have an off switch which disables it, some cars have various settings, and on some you cannot completely disable it (e.g., it will in any case reenable at highway speeds) such as the new Ford models.
Not sure about mechanical failsaves, but in any case, while nothing is 100% fail safe I generally trust automotive engineers or I would not step into a car. A hydraulic circuit can fail as well, for example.