[Justsignedup]

"I have no trouble staying alert this way when doing medium long drives. Long highway drives where autopilot is so good that it requires no manual interaction is where the trouble starts and I find it hard to keep paying attention."

Exactly!!!!!!

The trouble is when your attention wanes and you don't know exactly when you should be paying attention. What I found is the small amount of automation my car does is wonderful to keep my exhaustion down. When I drove for 4 hours in my 2012 prius, it was a chore, i had to do ALL the mental math myself. When I drive my 2023 CX-50 I have to pay attention at least 30% less, and that 30% is a massive difference, it feels like 90%. And any time my attention wanes, the car starts complaining because I am drifting or not putting enough immediate response to the road. It becomes a "pay attention quickly" wake-up call that happens within seconds of attention waning.

The worry is when the car doesn't snap you back into that attention mode, and you just trust it, right up to the problem.