Hy bud, excelent you are getting a Datsun, excelent choice, nice car, I love the sedans, I think I like them more than the coupe's, perhaps is the more inocent, or less pretentious looks that I like, both are cool, but my dream 1200(I have a ute/pick-up off road) is a sedan all lowered and fixed up, a little tasmanian devil over motored, 13 fat wheels and the like, nice!!!
About your mid-life thing, I do not think those exist, I think the seed of what we really like, our core, is molded early in life, and it never dies, it could be taken over for a while with other problems/events of life, but eventually it comes out. My Dad, he never showed any special interest in cars that I could see, a few months ago I calculated the year car models he had in front of him and might had loved to have when he was a teen and early 20 guy, and bought a book with the cars from those days, and bingo! he was so happy and surprised by my present, he says he has the book in his office desk and checks it out all the time, memories and a whole way of life long stored in his brain comes out like in a movie, that is what it is all about, we are and we have a core that will never go away, crisis? I would call it a rediscovery, re prioritization of your life's interests.
Jaime.