USE THIS PSYCOLOGICAL PLOY;
Have someone ELSE tell her the same thing. A neighbor, a girl friend could tell her to start the car first…THEN stow any stuff, THEN put on the belt.
If that doesn’t do it have your mechanic get technical with her. You know, kind of single her out and say " c’mere we need to talk." With books, charts or any other technical looking ‘‘evidence’’ they’ll appraoch her and state…“girl, dont’ do that, it’s going to break something soon,”
The ‘‘other person saying the same thing’’ is often a tactic to use if someone won’t listen to you yourself.
then it’s not percieved as your nagging.
also, do not gloat with “I told you so”.
( neighbor kid was mowing lawn with a side throw mower starting at the outside perimeter. He was facing the grass exhaust inward onto the grass not yet mowed therefore re-mowing all his clippings AND the the other grass AND compounding it by throwing all of that inward to be mowed over again.
I walked over to him and explained how to reverse hie path and throw the clippings outward so that he’s be mowing only new grass and not choking the mower with re-mowing all that old grass.
– which he promptly did, to his delight saw how well that idea worked.
Then his dad walks over to me and says “y’know, I’ve told him that same damn thing for the las six times he’s mowed the lawn.” )