Discuss Eva Norris, enrolled agent's answer to: How do I figure out what my car?s cost is for ...

First, in order to claim actual expenses and depreciation on your vehicle, you must be using it more than 50% for business as determined by your mileage log.  That percentage is used to calculate the amount of actual expenses and depreciation that you may claim.  Since you're using it for 2 different business, I would recommend that you use the mileage method instead.  You still need to keep a mileage log for each business to prove the mileage and do the calculations.