Hey Earl, we've had some cold weather out here as well and I've seen my temp go down to -29 celsius which is about -20F and that was within a couple of degrees of what the radio folks were saying. I don't see why the temp display would bottom out but maybe it does.

My hhr has experienced some really cold weather this week as well. It starts well and warms up well but it sure does groan a lot in the cold. There are squeeks and rattles everywhere. The suspension sounds terrible and I there is a lot of noise coming from underneath the body right around the rear seats/ behind the front seats.
I also noticed that the fluid in the struts on the rear liftgate freezes at cold temps and also the rear liftgate has trouble securing in a locked/latched position in this kind of cold. I tried to close my gate a couple times last night when I loaded my gym gear in there and it took a lot more force than usual to get it fully closed.

Stay warm buddy.

 

I do hear the 'extra' noise from the cold around the car but most vehicles have this. As for the rear gate, I have had no problems that I have noticed and i have used it at -20˚ just the other night... I have an 06 HHR 2.4 and have just about 50,000 miles on it right now. Still going strong even after the cold temps

By the way, I just checked and it is still -21˚ outside and it is almost 11:00 AM.... Not going to warm up much today.