Why does Tea Cake bring an old car to Janie?

When Tea Cake is first courting Janie, he disappears for a few days and then reappears in a battered old car. He tells her that he "'Brought me somethin' tuh haul you off in'" and says, "'Git yo' hat if you gointuh wear one. We got tuh go buy groceries'" (Hurston, 108). Janie protests that she sells groceries in her own store and that Tea Cake didn't need to find a car to take them somewhere else for groceries. However, Tea Cake responds that the groceries in her store are "'Not de kind we want fuh de occasion.'" He says, "'You sells groceries for ordinary people. We'se gointuh buy for you. De big Sunday School picnic is tomorrow—bet you done forget it—and we got tuh be dere wid uh swell basket and ourselves'" (Hurston, 108).
Janie is surprised and pleased at this because Tea Cake is treating Janie like she’s something special. Tea Cake wants to show Janie that he cares about her and that he can provide for her on his own and that he isn’t after her money. If the two of them had bought groceries from her store it would have been convenient and routine, and Tea Cake would have had to buy the groceries from her. Instead, he wants to buy the groceries for her. Tea Cake gets the old car so that they can go somewhere else to get food and then bring it to the picnic together as a date.