In chapter 2 Fadi has a problem, he looses his sister while trying to run to a truck to leave Afghanistan to go to the U.S. to Fremont California. This connects with the theme because it would be hard for everyone to get used to not having Mariam gone for awhile.
Several truck owners had created lifted trucks to compete in such events, and soon competition to hold the title of "biggest truck" developed. Description from pinterest.com. I searched for this on bing.com/images