This sounds similar to what I had recently with freeway driving in hold mode. Temp was on the 40s and I was running heat in max mode. 2017 with about 1100 miles at the time. I stopped at a rest stop and upon return found the car had a burnt electronics ozone smell and seemed smokey. I hoped it had come in from some of the big rigs parked near me and proceeded but noticed the smell a couple more times before arriving. I now have about 2200 miles and have not noticed the smell again but intend to bring it up the first time I get it in for service.