I'm curious what her reasoning is for you "needing" to trade it in. This would probably steer my answer.... but since you asked... if my wife told me I needed to trade in my 4Runner (or any vehicle I really liked)
I would start dictating to her she "needs" to trade her car in.
Maybe, just maybe, the light bulb will go off to mind her own damn business.
If not, then maybe this is your wife's way of asking for a new car (if you get one, then she can justify getting a new one... women are weird dude and every relationship is different obviously but the car you drive and obviously like is none of your wife's damn business in my opinion. It doesn't affect her life one bit (assuming she has her own vehicle).
Not to be critical....
I would keep what you have if you like it. Let your wife complain about it... she'll get over it.