You do not get a tax credit (or deduction) for paying off a vehicle loan; if you are still using the vehicle in your business, you can continue claiming the depreciation expense.
Form 4562 Depreciation and Amortization will show if you elected to expense any part of the purchase under Sec 179 (see Part 1 of Form 4562). Part 5 of Form 4562 will show any regular depreciation expense you claimed.