As mentioned earlier, “giving in” could refer to endless begging for OP to buy them cars. Or it could just as easily be DW giving in to their stubbornness to keep buying cheap clunkers for themselves, and wanting mom and dad driving something more reliable anyways.
The reality of the situation is…unknown, until OP chimes in again.
I got that impression as well. I just question if that pressure is coming from the in-laws, his wife, or even from himself (when I feel that I’ve established a standard, I often feel obligated to continue it even if no one else expects me to).
Speculating… but maybe “giving in” meant buying something new(er) vs. paying for repairs all the time on the clunkers they were driving if you are responsible for these “emergencies” when they happen.
is DW the only child? sound like she is. On the bright side, you are not living with your in-laws but hey, you could be as they get older.