> I got a software update that seemed to add auto steer to my non-autopilot model y.
All (edit: new since 2019) Teslas come with autopilot. “Full self driving” is an add on.
> I tried it a few times on the highway but it seemed erratic (switching off randomly and dangerously engaging regenerative brakes in the fast lane)
“Switching off” usually means that it can’t identify the lane it’s supposed to be in. Was this some sort of a rural highway, a highway under construction, and/or a poorly maintained road?
The braking is called “phantom braking”, and (since a very good update in spring 2022) usually only occurs when there is some sort of substantial deceptive visual issue like oil lines, asphalt sealant, a reflection of the sun, or visual mirages (when the road looks shiny/reflective due to temp diffs).
For me personally, phantom braking only happens on a couple of (crappy) roads at certain spots for me, so I just don’t use AP at those spots.
In general, AP is super consistent. Other than an overdone name, it works really well. If it was just called “advanced cruise control”, people wouldn’t be shitting themselves over the feature. It’s just adaptive cruise control with lane assist, two features that many cars have, and Teslas happens to have implemented quite well (imho).