You take either the 179 deduction, bonus depreciation, regular depreciation or a combination of the 3 on any "new to you" vehicles you purchase.
https://www.irs.gov/newsroom/irs-issues-guidance-on-section-179-expenses-and-section-168g-depreciati...
https://www.irs.gov/forms-pubs/about-form-4562
https://www.irs.gov/forms-pubs/about-publication-946
