You can claim deductible business auto/truck expenses in one
of two ways.
Rate: You can claim business miles
times the IRS mileage rate. IRS mileage rates for business activities are
$0.56/mile in 2014 and $.575/mile in 2015. You can add parking and tolls
to the mileage rate.
Actual Cost: You
can claim your actual costs including depreciation (or, for a lease, lease payments) times the percentage
that you use your car for business. Actual costs would include gas, oil,
insurance, repairs, etc. Payments on a note would not be deductible. The
cost of the vehicle would be deducted through depreciation instead (or
lease deducting lease payments if you lease it.)