Hello and thank you for your question. I would definitley keep track of business and personal miles. The reasoning is a decision will have to be made to use the standard mileage rate based on business miles driven or actual expenses. As you can assume the next bit of info is to keep receipts and track actual vehicle expenses as well. The IRS has issued guideance on mileage log standards and Intuit even has a mileage app. I will include a link from the IRS and TurboTax that has some very good detail information.
From IRS "Business Use of Car"
From Turbo Tax "Business Use of Vehicles"
Link to QuickBooks mileage tracker app
