You are reporting vehicle expenses as a contractor. Self-employment income and expense will be reported on IRS Schedule C Profit or Loss from Business.
Whether you claim the standard vehicle mileage or depreciation and actual expenses, the IRS requires disclosure of vehicle mileage and other vehicle information in Part IV of the form.

Reconstruct your mileage use as best that can be done. Your delivery vendor may have captured mileage information while you worked. Oil change receipts should list odometer readings at the time the work was performed.
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