Standard mileage rates are IRS set rates you can use to calculate the deductible cost of driving your vehicle for business, medical, moving, or charitable purposes.
Instead of tracking every actual car expense, you simply multiply the miles you drove for a qualifying purpose by the rate for that year. Using the standard mileage rate makes recordkeeping easier, but you must keep a log of your business miles. This method can save time and still provide a valuable deduction for people who regularly drive for work-related tasks.
For more information click in this link: IRS.gov