When my 12 year old daughter sits in the front passenger seat, the airbag indicator sometimes says on and sometimes says off. Is that based on the speed of the car or the fact that her weight is borderline for triggering the airbag off selection? Or some other cause?
There's a weight sensor in the seat. I think the dealer can adjust the sensitivity to make the ride safe for your daughter.
I'm currently shopping for a Prius... When I asked a similar question at the Toyota dealership, they told me it was a weight sensor which only turned the airbag on when it sensed over 70lbs. I don't know much about these cars yet but I don't believe I saw this feature as one of the "dealer editable options", theres a reference to them somewhere on this site.