the city, Gatsby lets Daisy drive his yellow car home while Tom drives the coupe. On their way home, Myrtle jumps out onto the road because she thinks Tom is driving the yellow car. Unfortunately, Daisy ends up killing Myrtle and drives away. Later on, Tom tells Wilson that Gatsby killed his wife, and Wilson ends up murdering Gatsby.

In The Great Gatsby, cars are a symbol of status and wealth, much like the American Dream. As we explore significant references to cars in The Great Gatsby, you'll notice an irony with using the cars as a symbol of the American Dream. 

1. When Nick was just about to leave his first party at Gatsby's, he stumbled upon a drunk driving accident (58 - 59)

But as I walked down the steps I saw that the evening was not quite over. Fifty feet from the door a dozen headlights illuminated a bizarre and tumultuous scene. In the ditch beside the road, right side up but violently shorn of one wheel, rested a new coupé which had left Gatsby’s drive not two minutes before. The sharp jut of a wall accounted for the detachment of the wheel which was now getting considerable attention from half a dozen curious chauffeurs. However, as they had left their cars blocking the road a harsh discordant din from those in the rear had been audible for some time and added to the already violent confusion of the scene.

When the man emerges from the wreck, Nick notices it's the man that he met in Gatsby's library. The man does not take responsibility for the crash - in fact, he not only mentions that he doesn't know much about how it happened, but he also doesn't know much about driving nor mechanics. Since the car was a new coupe, we can assume that the driver is wealthy. This incident foreshadows and complements Daisy's lack of accepting responsibility and carelessness in her car accident that fatally injured Myrtle Wilson. 

2. On their way to lunch, Nick admires Gatsby's manner in his car (69):

He was balancing himself on the dashboard of his car with that resourcefulness of movement that is so peculiarly American—that comes, I suppose, with the absence of lifting work or rigid sitting in youth and, even more, with the formless grace of our nervous, sporadic games. This quality was continually breaking through his punctilious manner in the shape of restlessness. He was never quite still; there was always a tapping foot somewhere or the impatient opening and closing of a hand.

From Nick's description of Gatsby in his car, we get a more descriptive picture of Gatsby's mannerisms that can be applied to his character. Describing his movement as "peculiarly American" can also be compared to the American Dream, which is also distinctly American. Nick describes Gatsby as restless and never still, possibly a comment on how he was able to make so much money in a short amount of time. His lack of patience could almost be a tragic flaw, considering how the novel ends. 

3. On a particularly hot afternoon, Tom, Daisy, Nick, Jordan, and Gatsby were in the house when Tom abruptly answered a phone call (123):

We were silent. The voice in the hall rose high with annoyance. ‘Very well, then, I won’t sell you the car at all…. I’m under no obligations to you at all…. And as for your bothering me about it at lunch time I won’t stand that at all!’

Following Tom's comment, Daisy cynically, "Holding down the receiver." Both Daisy and Jordan suspect Tom's infidelities (ironic, since Daisy is engaging in adulterous behavior herself). Nick, however, knows that Tom is in fact in negotiations in selling his car to Wilson, the husband of the woman Tom is having an affair with. Wilson, on the other hand, plans on using the car to remove Myrtle from the Valley of Ashes, as he suspects she is being adulterous as well. 

4. On their way back from New York, Tom, Nick, and Jay stop at the scene of Myrtle's accident. Wilson then accuses Tom of driving the car since he saw Tom driving the same car earlier (150):

‘Listen,’ said Tom, shaking him a little. ‘I just got here a minute ago, from New York. I was bringing you that coupé we’ve been talking about. That yellow car I was driving this afternoon wasn’t mine, do you hear? I haven’t seen it all afternoon.’

While Tom admits that he drove the car, he denies having any further knowledge about the car's whereabouts, even though he fully knows that Gatsby and Daisy were driving the car. This fuels Tom's suspicions for Gatsby even more, and he becomes determined to pin the hit-and-run on Gatsby. In Tom's eyes, Gatsby has not only taken his wife from him, but he has also taken his mistress. 

5. Up until this point, readers are unsure of what actually happened to Myrtle - that is, until Gatsby explains the situation to Nick (154): 

‘Yes,’ he said after a moment, ‘but of course I’ll say I was. You see, when we left New York she was very nervous and she thought it would steady her to drive—and this woman rushed out at us just as we were passing a car coming the other way. It all happened in a minute but it seemed to me that she wanted to speak to us, thought we were somebody she knew. Well, first Daisy turned away from the woman toward the other car, and then she lost her nerve and turned back. The second my hand reached the wheel I felt the shock—it must have killed her instantly.’

Once again, a wealthy person will not be taking responsibility for her actions - instead, Gatsby will take the fall for Daisy, which, in turn, leads to his demise. In this explanation, Gatsby recognizes that Myrtle wanted to speak to someone in the car (presumably Tom since he was driving it earlier). That yellow car was a symbol of her American Dream - her way out of the Valley of Ashes. Since she pursued her dream so quickly and imprudently, she ended up losing her life in pursuit of that dream. 

**Please note, due to differences in editions, the page numbers may not match up perfectly.**

Although I consider myself a very observant reader, I will admit that I wouldn't attempt to answer your question without a Kindle in hand.  Now that I finally have one, I can happily answer your question with quite a surprising result!

Cars are mentioned exactly 88 times in Fitzgerald's The Great Gatsby.

It's a high number, isn't it?  The large number of times truly surprised me.  I think it was surprising mostly because I was thinking of particular incidents that involve cars within the book.  I thought it might be fun to list them and then go into a little explanation of symbolism.  There are exactly 11 incidents that involve cars.  Here they are:

• Cars going into and out of the Eggs.
• Cars going into and out of the Valley of the Ashes.
• Wilson's exploits hoping to buy and sell cars.
• The car accident after Gatsby's party.
• Nick calls Jordan a "rotten driver."
• Gatsby shows Nick the famous yellow car.
• As Gatsby meets Daisy at Nick's.
• The group heads to NYC for thier hot confrontation.
• Wilson sees Tom in Gatsby's car.
• Daisy hits Myrtle and the car is deemed "the death car."
• Cars in Gatsby's funeral procession.

It is the second-to-last incident that has the most "car" words associated with it:  24.  Rightly so.  It's the most important incident of all.

Just to end with a little note about symbolism, I need to mention that Gatsby's creamy yellow car is usually pegged as a symbol of material wealth.  Let's look at its original description:

I'd seen it.  Everybody had seen it.  It was a rich cream color, bright with nickel, swollen here and there in its monstrous length with triumphant hat-boxes and supper-boxes and tool-boxes, and terraced with a labyrinth of wind-shields that mirrored a dozen suns.

In this regard, I also think it's REALLY interesting that at least part of Wilson's business involves "cars, bought and sold."  This shows that the man, living in the Valley of the Ashes mind you, desires that same material wealth, but can't obtain it for his wife, Myrtle, ... and to his own detriment.  Poor guy.

A more controversial take on general car-symbolism in this novel is that the car is a symbol of death.  If you scan the incidents above, you can see this works with many of them:  the "death car" being the most spectacular, of course; but even Jordan's rotten driving could have killed someone; the accident outside of Gatsby's mansion did cause a wreck; and a car did bring Gatsby to his grave.

And thus my theory lives on:  that the material wealth (symbolized by cars) of the Roaring Twenties validly foreshadowed the death (again symbolized by cars) of the stock market otherwise know as the Great Depression.

This incident occurs at the end of Gatsby's party in Chapter III. Nick walks down to the scene of the accident and sees Owl Eyes, the man he had encountered earlier in Gatsby's library. Since Owl Eyes is surveying the damage, Nick and the assembled crowd assume he had been driving, but he had not been the driver: "You don't understand . . . . I wasn't driving. There's another man in the car." At that point, the driver of the car, quite drunk, emerges from the car. He is also one of the party guests, but beyond that he is not identified.