When you use the mileage allowance to deduct your vehicle expenses, your depreciation is factored into the yearly allowance at the rate of about $0.26 per mile for the years in question here. So, your depreciation would be about $19,000 (73,000 miles x .26). You would deduct that from the purchase price of the vehicle times your business use percentage to arrive at the cost basis of the vehicle when you sold it. If that amount was less than the sales price, you would have a taxable gain to report on your tax return.