Jay Gatsby was at Tom Buchanan's mansion and while he was there he was showing his affection towards Daisy. Then Daisy started to panic that Tom was about to find out about them so she tossed a curve ball to Tom asking him if they'll all drive into city. So they just did that.
Jay Gatsby: She never loved you. Tom: Daisy is this true? Gatsby: Daisy honey just tell him that you never loved him and we can get this all over with ok. Daisy: I never loved you. Daisy cried Tom: Not even when I carried you from the pool so you shoes wouldn't get wet ? By the way Mr.Gtasby you don't know Daisy. Jay: SHUTUPPPP! SHUT UPPPP!!!!!!!!!!!!!!!!!!!!!!!
Daisy and Jay Gatsby storm out of the city and Daisy thinks that she might get some relief if she drove the car. So while they're driving Myrtle runs onto the street and suddenly out of nowwhere gets hit by the car while daisy was driving.