Will the new Prius do anything to avoid collision when changing into an occupied lane?

I'm 99.9% sure that the illuminated BSM is your collision avoidance / warning.

Your steering wheel may rattle a bit; if LDA is turned-on and you didn't signal. If you did signal, see above sentence.

 

I don't know about the car changing direction on its own, but you'll at least get some strong beeping if you signal in the direction where a car already is. It's happened to me at least once where I signaled a little early as either I was passing or being passed.

 

This actually happened to me today. So many beeps... easy to ignore. I started to change lanes into somebody with all of the stuff going off. Ultimately, the car steered away and I finally noticed the other guy. Probably would have hit him if it didn't do that. Very glad for the feature. I don't know what setting it was that made that happen, but I have most of the safety things still turned on.

I also once started backing out and there was a car coming and the car hit the brakes for me and prevented me from backing into the other guy. So the features have potentially saved me twice already (embarrassed to admit).

Gotta love this car .

 

Regarding lane changes - did anyone actually use already the Lane Change Assist? It would only change if the lane is free anyway - so not much room for mistakes. I cannot imagine myself using it often though...

 

Huh. Didn't even know the car had that. I'll have to give it a try, though I agree I can't see myself using it often.

 

Here are the manual pages for the LCA.