Vehicle automation aims to improve safety and comfort, but using partial driving automation safely can challenge drivers. To investigate how drivers trust and rely on the automation, we conducted a field study with 100 participants. While driving on a public highway, they rated their trust and commented on their interaction with the automation systems for longitudinal (adaptive cruise control, ACC) and lateral control (lane-keeping assistance, LA). Our results show that trust in partial driving automation increases continuously by using it. Comparing the automation systems, we found that drivers trust and use the ACC more than the LA. While driving, drivers express more liking statements about the ACC and more disliking and criticism statements about the LA. However, the number of mentioned interaction difficulties is higher for the ACC. We discuss possible reasons for the observed differences between the longitudinal (ACC) and lateral (LA) automation.