If we all bought and drove our cars by our age, I should be driving a Toyota Camry and wearing the space shuttle sunglasses
. However, if you can afford (and respect) the Z34 then get it.
Every age of drivers cannot be represented by one individual. Not all 17 years olds drive ricers and not all 60 years olds drive "luxury, cushy cars", so get whatever you want and don't give a $hit what others think.
Good Luck with your decision and oh by-the-way, welcome.