I actually like this thread a lot. Lots of good perspective and no bull ****. Like OP said, it's completely situational and personal. One common theme I see in this thread is the upgrade to the new Z - just keep in mind, although it's still a Z at heart, it's a different power plant. Do you want FI over NA? Will you enjoy it? No matter what anyone says, the 370z is an OG. Also, at the end of the day, it's a gamble to do something right now and expect things to fall into place in the future. Just some things to think about before pulling the trigger on whatever it is that you decide
If you actually want the new Z (or whatever new car for that matter) and have the luxury of utilizing another car to get by in the mean time, I'd say definitely go for it if the deal is legit! As long as you can avoid any mark-up, I think you'll be fine. Saving money and being conservative over wants and needs is absolutely sound advice, but if you can afford your wants, then...YOLO.
All I'll say is there's nothing like NOT having a car note!