I had this question posed to me recently so thought I’d offer up more on it here.
If you use your car in your job or business and you use it only for that purpose, you may generally deduct its entire cost of operation (subject to limits). However, if you use the car for both business and personal purposes, you may deduct only the cost of its business use.
You can generally figure the amount of your deductible car expense using one of two methods: the standard mileage rate method or the actual expense method. If you qualify to use both, then you may want to figure your deduction both ways beforehand to see which gives you