In Virginia, every car sale between the public and a dealer must use a Buyer's Order for the sale that states that if the loan does not go through, and the dealer asks you to bring the car back, and you bring the car back within 24 hours, you are entitled to all your down payment and your trade in. If the dealer tries to get you to sign another, more expensive contract, do not do it unless you really want the car and can afford the new contract. There is absolutely no obligation for you to go through with the purchase unless the dealer offers you the same terms as you originally agreed to. There should be no deductions from your down payment whatsoever. Just get your money and go somewhere else.
If the dealer fails to give you your tradein (or the same amount of money that it was worth) or your money back, then it has violated Virginia law, and you can sue them and get legal fees as well, and possibly up to three times your loss! Do not try to do this yourself, once the dealer calls and asks for his car back, give us a call to help you through this process.
Important, before you give the car back, get all purchase documents out of th car for your attorney's records so we can make sure what everyone agreed to. Check your credit report to make sure it has not reported you as delinquent. If they have reported you as late this could violate federal law.