This is my 5th northwest Indiana winter in my volt and I've grown accustomed to the battery range degrading with the low temperatures. However, in the past 4 winters I've never had a battery range less than about 28 miles on a full charge. That range will get me to and from work without charging with plenty to spare, or has in the past. I did notice this summer that even on warm days my battery range seemed to have decreased by a few miles per charge. That is very apparent now that cold has set in. I'm lucky to get 20 miles on a full charge now. My routes throughout the area have not changed nor have my driving habits. At what point do I take it to the dealer and ask what's going on with my batteries? The other fact is that the volt has experienced much harsher temperatures that we have seen so far this winter and never had this low a range. The temperatures have actually been rather warm for this area and this time or year with temperatures reaching mid forties and even fifty a couple of days in December. We are currently in the teens but this range issue has been present even when temperatures were in the forties.