Well, time will tell if I'm having my first experience with a bad vial of insulin. I noticed yesterday that the floor of the car was a bit warm, but certainly not hot or anything like that. I've also been using the ice pack that comes with my bag, which is specifically for insulin. We can't seem to keep the cooler really cold, though - it may be broken, so the ice pack has gotten increasingly warmer.
Anyway, that brings me to my first experience with rage bolusing. I figured I could be getting unexpected highs because of sitting in car all day, but when it didn't respond to more insulin...I took some more. Luckily, I only went down to 70 and didn't have any serious lows. After this happened twice in a row, I took more insulin with meals, but was still unexpectedly high. So I'm throwing out the old vial and opening the new one. I hope this one doesn't go bad because I don't have any more. Hopefully the new vial will solve the problem!