As the group including Daisy, Jay, Jordan, Tom, and Nick are preparing to go into the city in chapter 7, Daisy says that she and Jay will go in the Buchanan's car and the other three can go in Jay's very obvious, ostentatious cream colored car. Tom has to stop to get gas and he does so at Wilson's garage. While there he facetiously says to Wilson that he'll sell him this car, implying that it is his. More significantly, Myrtle sees the car from the window of her apartment. She sees Tom in it along with the other two passengers. She also makes the assumption that it is Tom's car and she assumes that Jordan is Daisy. The implication of that last assumption is that it makes her irrational. Myrtle is already naive enough to believe that Tom really cares for her and the sight of her boyfriend out with his wife while she is locked up in her apartment sends her over the edge. Later that evening, when Daisy is driving back from the city with Jay in her own state of heightened agitation in Jay's car, Myrtle runs out into the street when she sees this obvious car and thinks it is again Tom who is driving. She is hit and killed. That mistake in identity costs Myrtle her life. The incident is part of the mistaken identity thread in the story though. It is also part of the wastefulness thread.