Daisy is driving Gatsby's car when she hits and kills Myrtle. Earlier, Myrtle sees Tom driving Gatsby's car into the city, so when she sees the car again, she thinks it is Tom driving. Not until the end of the novel do readers learn it was Tom who told Wilson that Gatsby killed Myrtle. According to Tom, Wilson came to the Buchanan house with a gun seeking answers, and Tom told him it was Gatsby's car that had hit Myrtle.
