The author's secondary purpose is the following one:
A.To persuade readers that they should do something exciting over the summer.
If the author chose to write about what it takes to be all set for a road trip, it means engaging in such an activity is something she probably enjoys doing. The very fact that the author knows about the procedures to be followed shows it. Therefore, if the author truly likes going on road trips, that feeling of hers will be there somehow, at least between the lines. Whoever likes something tends to try to share it with others and convince them to do the same.
