Help me to help my mother spend all of her money on a 6MT N52 Z4.

I come home to my mother wanting to buy a new car. Test driven were 7 cars (all manual): Acura ILX 2.4 (leather laden, overpriced but good Civic Si), BRZ (too stiff and boy racer-ish), 328i sedan E92 (no sunroof, kinda big), Audi A5 (boring and pricey, expensive maintenance), 128i 6MT (fucking perfect but somehow a 2008 is ancient), E90 328i xDrive coupe (felt A5-ish and is overpriced), and finally the Z4: 11k miles, good price, gray/black, N/A I6, M-Sport. Was honestly great and the only sports car she'd buy. Also, probably now the only car she really appreciates. The problem is that 3 times a year, she might want to take some people in her car, and it would be a great travesty to be without rear seats. So she'd keep the Beetle worth $2k. Here's the best part: I'd pay for another parking space, and get the Z4 after 8 or so years. The problem? No parking spaces at her building for sale. Maybe not even for rent. I love the cars I have owned and worked on, but this thing is so out of their league (by a price factor of 10) and the thought of ever owning such a formidable machine for the price of a parking spot is astounding to me. So, where's the solution here? Help would be greatly appreciated here. The Z4's CPO and a good deal.