LitCharts assigns a color and icon to each theme in Paper Towns, which you can use to track the themes throughout the work.
Perception vs. Reality
Authenticity and Artificiality
Human Connection
Leaving Home and Growing Up
Friendship
Summary
Analysis
Quentin and Radar discover, as the hour approaches when they are supposed to trade places with the still-sleeping Ben and Lacey, that they have consumed too much Bluefin to imagine falling asleep. They agree to let Ben and Lacey continue sleeping. Driving on the empty interstate feels easy and pleasurable to Quentin, but it occurs to him that, while Margo may have been able to enjoy this drive in solitude, he could never feel so happy and peaceful if he were traveling alone.
Quentin has often failed to appreciate his friends, but he sees now how his happiness is tied up in them. Although he acknowledges that Margo may not have needed or wanted companions for this journey, the thought of her driving this route by herself seems lonely and sad when compared to the boisterous camaraderie of the minivan.