Every year there are far too many deaths of children and pets that resulted from accidentally and/or purposefully being left in a vehicle. I propose that the automotive industry be required to come up with a reliable alarm system that would notify the person in possession of the keys and an alarm that would alert the general area around the vehicle, that there was movement within the vehicle, from a child or pet or other vulnerable person, after a few moments of the vehicle being turned off.
http://www.rspca.org.uk/allaboutanimals/pets/dogs/health/dogsinhotcars
http://www.kidsandcars.org/heatstroke.html
Clearly awareness is not enough.