Tell her the insurance won't allow newly passed drivers on a 3.5 litre V6.
People keep mentioning that you should buy her a runabout, but as she wants you to sell the zed, I'm assuming she wants something newer to drive around in. As the car is yours, i assume you bought it/pay the loan and she doesn't. My opinion would be that if she wants a newer car then she should buy one herself and keep her nose out of what your driving