Interesting. So many stories of people loving AP. My experience was different. I just wasn't very impressed.
My M3 is used mostly for commuting from Oakland to SF and back every day. So I travel through neighborhood/residential, city, and 3-4 different limited-access highways in 40 minutes each way.
(NB: I should mention that I do not consider driving on public roads to be a chore or particularly mentally taxing as a baseline. Most people are garbage drivers, so I consider my job to get from point A to point B without letting anyone try to kill me, and that's all. I did some quantitative studies long ago showing that defensive/low-aggression driving adds less than a minute to my 40 minute commute. Long following distances, as few lane changes as possible, identify and avoid poor drivers, look way ahead, always leave an out, zero aggression.)
Anyway, my observations of AP were:
- When no traffic present, was about the same as regular cruise control
- In heavy traffic, reduced mental load by maybe 10%ish (again reiterating that I don't get particularly anxious in the first place)
- In flowing but heavy traffic, AP does not drive defensively. It does not leave itself outs or set itself up for smoothness (e.g. I know my target lane for ease of exit, and I switch to that lane whenever an easy opportunity presents itself). AP would sit in people's blind spots, leave inappropriate follow distances at low speeds which would lead to me getting cut off, etc. It doesn't anticipate that the guy to the left is getting twitchy and are clearly going to dive-bomb the next exit so you better give him some extra space or he'll do something stupid. Etc. It stressed me out how "dumb" AP was vs. just driving myself.
- I tried using AP various places, but really the only place I could use it reliably was on the Bay Bridge, only after the toll plazas, and only after the post-plaza merge, which is a total of like 10 minutes of my 40 minute commute.
So I figured it was marginally valuable but probably not worth $3,000, and then after some strange behavior chasing lane lines, I decided I trusted it less than I trust myself. I guess I could see some limited situations where it could be nice, especially if it were free. But in general, I feel there is a long, long way to go with the technology before it would be valuable for my situation.