I think his approach to financing a new vehicle is wise...the high cost of said vehicle is another story...
...that said, us old geezers got along with more modest "starter" vehicles when we were junior execs, despite the good starting income.
You look today, and high school kids have better rides than a lot of us...and it ain't just the suburban kids!
Go find the thread about the age of members of this forum...we have a healthy group of members under 20 with late-model MBs...so your friend is under a LOT of peer pressure!