A better plan is to ditch the cranky X5M and buy a MY P.
‘I went from an X5 3.0D Msport to a MY LR , and `I don’t miss the X5 at all !
Perhaps I miss the fabulous split tailgate, but that’s it.
I had a X5D, and also a X3 M40. Depending on the options the OP has on their X5M, its likely it "drives a lot better than" a Model Y P. Dont get me wrong, I really like the Model Y P I got for my wife in march of this year, but the one thing it doesnt do as well as the X3 M40 it replaced, is handle canyon carving.
Our X3 was fully loaded, with every option BMW offers for an X3 factory ordered, except for the tow hitch. With the adaptive suspension the X3 had, when placed into sport mode (or the customizable suspension / throttle setting you could do if desired), the X3 drove a lot better than the Model Y P we have now.
Note it wasnt faster in a straight line, but much less body roll, etc. My wife doesnt care about any of that, and I decided I didnt care either since the model Y is her car. I figured if it bothered me a ton later, I would do something with the suspension.
Its likely that the OPs X5M drives a lot better than a model Y P, and I would agree with them on their current desire to replace their daily driver with a model 3 vs replacing the X5M with a model Y.