what if someone wants to drive your Z ??

Ventruck

If you don't want them to, don't. You committed tens of thousands of dollars to it. Test drive is more of something you'd offer, not ask for imo — even if it's econoboxes. If they trip, I doubt your friends circle or whatever would be stupid enough to side with him/her.

In the case of more favorable friends I'd only be open to this if they were legit mulling their options. Or, not to be a snob, but if they had something of equivalent performance, yeah a "trade" test drive is probably on the table. Kinda boils down to if they're proficient drivers, and they can absorb something going wrong by their fault. On the other hand, I'd more easily trust a specialty shop mechanic or an established forum member here — obviously because they have the same car and perhaps with a higher end build.

I would hate to have that awkward pit of someone I'm on good terms with owing me big and possibly screwing up both our records but you have to sugarcoat it as "no worries this will get sorted" "it's just a car" and that crap that most people in their right minds don't actually mean unless they've got piles of cash to replace things.