In The Great Gatsby, who are the speakers in the quotes below, and what is the significance of this dialog?" You're lucky that it was just a wheel!...

This exchange of dialog in more context is found in Chapter III following Gatsby's party. As the guests are leaving, one of them drives his car into a ditch, knocking off one of the car's wheels. A crowd gathers at the scene. When Owl Eyes (the man Nick had talked to in Gatsby's library) steps out of the car, people assume incorrectly he had been driving. Owl Eyes, in the confusion, says he knows nothing about driving. When told he shouldn't have tried to drive at night, he says he hadn't even been trying--meaning he hadn't even been driving.

One of the spectators then strongly criticizes Owl Eyes for being so careless. In telling him he was lucky that only a wheel was damaged, the spectator is suggesting that he could have had a much more serious accident, perhaps hurting someone.

Owl Eyes protests that the accident wasn't his fault; the driver is still inside the car. At that point, the driver steps carefully out of the car. He is obviously very, very drunk, so intoxicated he does not even realize he has wrecked his car.

This scene emphasizes the excessive drinking and irresponsible behavior associated with Gatsby's parties that summer. Nick had commented earlier on the carelessness and chaos he had observed at Gatsby's party:

. . . [Gatsby's guests] conducted themselves according to the rules of behavior associated with amusement parks.

The drunken driver in this incident appears to be a typical party guest, and Owl Eye's confused and nonsensical conversation with the spectators is typical of the party that has just ended.