Married for 21 years. I just turned 48 on 4/20 and the M3 has been my "gotta own one" car since I was 14.
Wife loves cars and I get phone calls while she is commuting sometimes when she sees a R8 or Bentley or Ferrari in a color she thinks looks cool.
I got her hooked on original Top gear when we were newly married and her only two questions when I told her about the new M3 was "you are getting it in AWD?" And "no manual" (she never learned manual)
We have no kids so it's not like we need to save for college.
I don't think any car has a strict rule for a specific age. If there is one thing I believe in it's that you just need to enjoy stuff for yourself. If you like it that is all that matters.