ok, here is what I noticed, when getting into the car it initially shows no service then quickly goes to full LTE, so it seems that the car is turning the signal off when sleeping for some reason
Is that definitely just when you get into the car? I'm just making the distinction from entering the car and taking it out of Park ... because that's what it's supposed to do in that circumstance. If you hadn't moved out of Park then it's certainly an issue.