I remember when I first got my Bolt, the range didn’t quite match the advertised 259 miles either, and I was convinced something was wrong. I kept it charged in a warm garage and drove pretty consistently, yet the range kept dropping.
The dealer pointed to cold weather and my driving habits, too, and it felt like a brush-off at first. But after some digging, I found that colder temps really do impact range more than I'd thought. Heating the cabin alone uses a lot of energy, and even the battery itself doesn’t perform as efficiently in the cold. Over time, as I adjusted, it stabilized a bit more. It can be frustrating, but I did notice improvements with slightly warmer temps and small tweaks to cabin settings.