Unless this purchase is for business purposes, there's nothing for you to enter.
That said, you may be able to deduct the sales tax you paid on the vehicle, but only if you itemize your deductions using Schedule A, and use the Sales Tax deduction rather than State and Local Income Tax deduction.
Because of the tax changes that occurred a couple of years ago, most people do not itemize deductions. The Standard Deduction amount was raised substantially, and many people no longer itemize.
Here's a little more info on the "major purchase" sales tax deduction:
How do you define major purchase or major item for the sales tax deduction?
If you purchased this vehicle for business use, please post back and I'll give you more information.
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*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***