I find the forward collision warning to be perfectly tuned. Mine is set on "medium" and it honestly has never falsely alarmed. So I'm wondering, how far back in time is it available? Do all Model S cars have it starting in 2012? Or only those with AP1 hardware? We are shopping for a used MS for my wife, and this car may eventually roll down to my young adult son, and he is the one who really needs the safety assistance. Planning ahead. Thanks.