Keep your current cars in addition to the 3, and tell her you are spending an extra several hundred dollars a month betting on horses at the track because you met "some guy" at the local pool hall who "has never picked a loser." When she approaches you, don't agree to stop, and keep asserting that you are just about to "hit it big" and that "soon, all our problems will be over, little lady." Then after 18 months when you are on the verge of divorce, tell her "jk we have had a Tesla since 2018." You will then both laugh about it, and you will be able to say "remember that time I surprised you with the Tesla?" for the rest of your life. Good times.