If you use your car for business, you can deduct the business-use portion of your vehicle costs. There are two methods: the standard mileage rate (multiply business miles by the IRS rate) or the actual expense method (track real costs like gas, insurance, and repairs). You can't use both methods for the same vehicle, and switching methods later has restrictions. Keep a mileage log with dates, destinations, and business purpose. Commuting to a regular workplace is not deductible.