If this helps, see https://bradfordtaxinstitute.com/Free_Resources/IRS-Mileage-Rates.xml.aspx and scroll down a little more than halfway to see the depreciation per mile rates for each year back to 2003. If you have tax returns back that far, then you whould have worksheets for each year that will break down business miles and personal miles. That's assuming you used Turbotax and took the per mile deduction each year.
