According to IRS publication 463
If you use your car for business purposes, you ordinarily can deduct car expenses. You generally can use one of the two following methods to figure your deductible expenses.
Standard mileage rate.
Actual car expenses
Actual car expenses include: Depreciation, Licenses, Lease payments, Registration fees, Gas, Insurance, Repairs, Oil, Garage rent, Tires, Tolls, and Parking fees
Business and personal use. If you use your car for both business and personal purposes, you must divide your expenses between business and personal use. You can divide your expense based on the miles driven for each purpose.
Example.
You are a sales rep for a company that sells widgets and drive your car 20,000 miles during the year: 12,000 miles for business and 8,000 miles for personal use. You can claim only 60% (12,000 รท 20,000) of the cost of operating your car as a business expense.
All of this information can be found on IRS.gov and always consult a CPA to get the maximum amount of deductions your entitled to by the law. The types of deductions and tax strategies can vary depending on the type of legal entity you have your business setup as. Again consult a qualified CPA and or Tax attorney to discuss the options you are legally entitled to under the tax code.
I hope this helps and good luck.
R