I have no idea what the COAST is so once I know, maybe I'll try it to see if we have issues.
Watch the tachometer when your supposed to be "coasting". Mine lingers around 1000rpm when coasting and the tranny doesn't downshift as I slow.My GV80 stopped coasting about 9 months ago and the dealer said that it was still coasting despite the word "coasting" no longer displaying on the dashboard. I am going to revisit the issue when it goes back in for service in a few months as I can tell that it is not coasting like it used to. I don't think they know what the problem is. Good luck!
its in the custom and eco settings.. allows the car to coast when you come off the gas.. when it works is improves gas millage. and the car coasts very well..I have no idea what the COAST is so once I know, maybe I'll try it to see if we have issues.