temperature app

We are hearing more and more about children, babies and pets being left in cars which have elevated to extreme temperatures causing the death. We live in a busy society where people are distracted, preoccupied in conversation, in a line up and/or just do not realize how quickly a vehicle can turn into an oven. Some people think they will only be a minute to run into a store and end up being 30 minutes or more. As we cannot keep the vehicle running with the air conditioner on, I thought you have the means to develop an app which allows people to know the internal temperature of their vehicle and signal them when it reaches a particular temperature as a warning. I thought it could also alarm on their keys for those not having a smart phone.
It could also allow the person to start the vehicle with Air conditioner on/adjust Air Conditioner immediately before they can get to the vehicle.