First of all, you can only deduct depreciation on the vehicle if you are reporting self-employment earnings, not wages listed on a W-2 form. In that case, you need to go to the Business Vehicle Expense menu under Business Expenses in the self-employment section of TurboTax, where you will be asked questions regarding the vehicle to see it it qualifies for special depreciation. If so, you can choose the election to use the special depreciation allowances.