Tell her what you want to do and why. If she agrees to consider it take her to the dealership (a little "prep" with the dealer principal and sales guy can go a LONG way on this) and ask her to at least go on a test drive with you, or ask her to drive it as well. If she doesn't agree to buying it then you have to abide by the decision. Your marriage is worth a lot more than any Porsche will be...