U.C.C. to the rescue, perhaps?
UNSATISFIED…
Whether by chance or by design, the fact that the subject matter of the contract (the car) is still sitting on seller's lot may come to your aid in avoiding the contract on a purely knit-picking technicality, which I must emphasize will have to be argued succinctly in order to succeed.
That a contract was formed, there is no question and I agree 100% with Proserpina's and Betty3's take on this; even more so considering that the reason behind your decision to avoid the contract is buyer's remorse than a cognizable rule of law. But the colloquial, laymen concepts of cold-feet, fair dealing, and sense of fair play in contracts apart, and if argued properly and succinctly, you can invoke the authority of Sections §2-401 - §2-403 and §2-501 - §2-515 of Article 2 of the Uniform Commercial Code. Otherwise known as U.C.C., these sections deal mainly with Title, Risk, and Insurable Interest with title holding as your central argument.
U.C.C. controls and regulates contracts for sales of goods the essence of which is the
transfer of ownership (title) of the goods from the seller to the buyer, which in turn completes the contract. That means that even though a contract is formed, it is not complete until and only until the title of the good has been transferred from seller to buyer.
In Article 2, U.C.C. also took pains to streamline the process and eliminate ambiguities of yesteryears by defining for the parties to a sale of goods contract exactly when title passes from seller to buyer (and in the process determine the rights and duties of the parties between the time a contract is formed and the time the goods are actually received by the buyer) in U.C.C. 2-401(2) which says:
"…unless an agreement is explicitly made, title passes to the buyer at the time and the place the seller performs the physical delivery of the goods…!"
I direct your attention specifically to the provisions contained in §2-401 (4) of Article 2 of U.C.C. which says in whole:
A rejection or other refusal by the buyer to receive or retain the goods, whether or not justified, or a justified revocation of acceptance reverts title to the goods in the seller. Such reversing occurs by operation of law and is not a "sale".
Hope you can make sense and a go of it!
fredrikklaw