Unfortunately, you would have no claim against eBay motors because the real eBay was never involved in your transaction. You have been taken in by a very popular scam that has nothing to do with eBay.
Here's how it works, though there may be some minor variations:
You see a desirable vehicle in an online advertisement on Craigslist or some other advertising site or online auction. The cost is way below its book value. The seller is typically either out of your area of the country or advertising it from abroad. He can't let you see and inspect the vehicle, nor will he allow an agent of yours to come see it on your behalf. He may say that he's in the military and about to be deployed or has had to move out of state quickly due to a divorce or job change, but whatever the excuse, there is no possible way you or your agent can come and inspect the car that you are looking to buy.
But don't worry, he assures you. The car is just great and you will be able to have 5 days to inspect it during which time you can send it back. Meanwhile, your money will be held by an eBay Motors agent and you will be protected by eBay while you look it over. If you decide to get the car, he tells you that eBay will then release your money to the seller. He may even "throw in" the cost of shipping and insurance, to sweeten the deal because he is in such a hurry.
You'll get an email or call from "eBay" providing you with payment instructions. That will usually involve a wire transfer using Western Union or MoneyGram or a money pak card payment to go to the so-called eBay agent. Then you sit back to wait car. By the time you figure out that it's never going to arrive, your "seller"and the "eBay agent" have disappeared without a trace and your money along with him.
You try to find him, but none of the information you got turns out to be true. You contact eBay and they don't know what you're talking about because as you come to learn, the real eBay never acts as an escrow service to hold goods or money buyer or seller. eBay protection extends only to what goods you actually purchased in an eBay auction or fixed price listing and not with any items purchased off site.
Here is a warning from eBay Motors about these scams.
You're the victim of a crime. If you could find the actual seller, you could take him to small claims court to get your money back, or you could have the seller prosecuted. But your legal remedies depend upon your being able to find your seller.
Typically, the scam is run by a professional thief who is operating from a foreign country and who has mastered the art of disappearing into cyberspace, because everything you know about him will prove to be false and he has required payment by some means which is untraceable. This means you will only get your money back if law enforcement can figure out who and where your scammer really is and bring him to justice. In most instances, these scammers get completely away with their crime.
You need to report the fraud to your police, to the FBI online at their Internet Crime Complaint Center at IC3.gov and to the Federal Trade Commission at FTC.gov. Failing that, unless you wish to enlist the service of a private investigator, any other steps you can take would primarily be to warn others.
I know the above is not what you hoped to hear, but I can give you a small bit of consolation: when you are a victim of a crime, your unreimbursed losses are tax deductible. So at least you can get some of your money back in the form of a deduction when you file next year's taxes.