To be able to deduct vehicle expenses you must have a written record of your business use. You at least need the date, location, and purpose, of the business travel. You can deduct either mileage or actual cost, however mileage will usually get you the largest deduction (unless you purchase a vehicle this year and use it 50% or more for your business). You Cannot switch back and forth from mileage to actual cost.
Note: Please complete this section on a separate sheet for each vehicle you used in your business.