Well, it's going to depend on the feature. Slightly improved UI on the radio's touchscreen is a bit different from Tesla's autopilot.
In the case of autopilot, I'd say similar to a drug study, as it's something that can cause serious harm or death to the human subjects involved. Tesla should have an IRB for ethical monitoring, there should be a small trial group initially (and very gradual rollouts to larger groups), participants should receive informed consent at a Tesla store with emphasis on the risks and what's necessary to use the feature safely, and someone should have the authority to pull the plug on the study if it proves too dangerous.
Given the state autopilot is reportedly in, I'd say right now no one should be using it without an in-person training at a Tesla store to emphasize the proper usage of it.