If the vehicle was 100% business use - all mileage was business mileage. There can be no personal gain or loss. So you can skip the rest. Personal use is all non-business mileage divided by total mileage. If there was personal use, the trade-in value (the selling price) is split between business and personal use. So if the personal portion of the proceeds less the personal portion of the cost (depreciation applies only to the business portion ) is a gain, its capital gain that is taxable. If a loss, most likely, it's not deductible.
If business use varied over the years, I don't think Turbptax can properly handle the sale on the vehicle worksheet.
