Obviously the old car will NOT be worth more in 2 years.
But if you look at its two year depreciation VERSUS the depreciation on a new one! No way you're money ahead trading now.
But really your options are to try to reason with her or give in. And since I don't know you or her, logical thinking may be of no assistance.
True. But you are going to replace the battery shortly and some belts and other stuff. You will be back on full warranty as well.
Plus the vehicle they are looking at getting is so much better to drive and much more functional in all likelihood.
Pride has the money.