There is no special tax credit just for getting married. You can file a joint return with your spouse and get the married filing jointly standard deduction of $12,600, plus each of your $4050 personal exemptions on your joint return. You may be able to deduct sales tax on your new car if you itemize and do not deduct paying your state income tax.
You can enter the sales tax you paid for the car you purchased in 2016 by going to Federal>Deductions and Credits>Estimates and Other Taxes Paid> Sales Tax. You will be asked if you paid sales tax on a major purchase, and you will be able to enter the sales tax you paid for your new vehicle.
Sales tax is an itemized deduction. If your state has a state income tax, you have to choose between using the deduction for your state tax paid OR the sales tax deduction, whichever is higher. The TT process will suggest one or the other as you prepare your return.