You may be mixing up different concepts ... you choose the standard deduction OR itemized deductions (sch A) and you can choose the better option each and every tax year.
Then the mileage deduction on the Sch C ... you can choose the standard mileage rate OR the actual expenses option for the vehicle expenses. If you start the vehicle with the actual expenses option you are STUCK with that choice for the life of that vehicle. If you had started with the standard mileage rate in the year you placed it in service then you can flip flop between the 2 options as you like.
