I'm so sorry, msbelle. I think you can wrap her in a blanket and keep her someplace cool/cold and dry -- if your car is the only option there, then I don't see why not. This must be so hard.
And then in the morning, call/go to the vet to find out about options for her remains. I'm so sorry. How awful.
But I think the safest thing is to wait until the morning to drive anywhere.
I will make any calls to see if there are services to pick her up.
Oh, that's a good thought, Cass. I hadn't thought of that.