How do I report what I paid for my car when I financed it?

The sticker price or the price you paid for it.   For that section, it doesn't matter if you financed the vehicle or not.   TurboTax uses the cost of the vehicle to determine depreciation amounts you can deduct.   

The IRS offers two ways of calculating the cost of using your vehicle in your business: 

• The Actual Expenses method or 
• Standard Mileage method. 

Each method has its advantages and disadvantages, and they often produce vastly different results. Each year, you’ll want to calculate your expenses both ways and then choose the method that yields the larger deduction and greater tax benefit to you.

For more information, see Getting the Biggest Vehicle Deduction and for even more information, see Business Use of Vehicles