The majority are offering you advice a father would offer a son, and I think you should treasure that.
At your age, forgive me for being blunt, but all you want is to find justifications for getting a purchase of something cool, better.
I would get what I could for the current landy, and shop for a reliable car that suits your finances and situation....that includes a Nissan (towncar) at 5 grand.
Cheap to run and maintain, tuck my ego away, save like buggery, adore my wife, target the real estate with an obsession like passion and free myself from as much debt as possible.
Win respect from my wife in the long run
Win respect from my in laws immediately
win respect for myself in a MAJOR way in the very near future.
Create a life habit that will see me through hard times.
It's only my opinion, but think for a minute. What happens if it turns out that the next three years turn out to be the hardest we have seen in 50 years?
No time to borrow money on an asset that costs money as it shrinks in return!!

