Depends. If it is Level 5, it does not matter. At any lower level, I would say not. The driver is required to be alert and ready to take over. In my experience, I have to be really sober and wide awake before I dare to turn on auto steer. My wife refuses to use even TACC. I personally think TACC is a no-brainer. Not only does it prevent wear and tear on the driver's eyes, but also it eliminates the chances of inadvertent speeding.
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