You have the choice between the Standard Mileage Rate and the Actual Expenses. If you use the Standard Mileage Rate (which is easier and usually give you a better deduction), you can only use that rate plus loan interest, tolls/parking fees, and vehicle registration tax (those expenses are then prorated by you business percentage).
If you use the Actual Expenses, you add up all gas, repairs, maintenance, etc. and you deduct your lease payment (minus the "inclusion" amount) OR if you are buying the vehicle you depreciate it (not deduct the payments) and also deduct the loan interest (plus all of the other expenses).
