The exact cases where human reaction times fail are already taken care of by local subsumptive AI† in cars. For example, collision avoidance is “AI”; lane-keeping and adaptive cruise-control are “AI”; etc. For that matter, an automatic transmission is “AI” in the sense of abstracting away a clutch and gears under a prediction of when you’d want them used.

† ...which doesn’t actually imply anything to do with Machine Learning. Your computer downclocking when it overheats rather than catching on fire, is an example of “subsumptive-architecture artificial intelligence”, even though it’s a hand-coded algorithm doing the subsumption. The “artificial intelligence” in this case refers to the emergent property of the layered subsumptive processes, not to the processes themselves.