Yaw sensor, might happen but that's not a frequent issue, so far only that time.
Since they are mechanically similar, the symptoms might be the same like your friend's car if it happens.
But I am quite surprise actually if you say comfort of conti. I have not sat in one until last week my wife ask me to change tyres for one of her company car. Is a new model ES250 about a year old and it don't ride like a conti.....lol
Huh? Ride quality that bad? I have never ridden one before while moving, only sat inside them while parked during roadshows. Feels very nice inside.