The standard mileage deduction is not allowed for business owned vehicles. Businesses are required to use depreciation and actual expenses when reporting vehicle expense on the business return. Businesses are allowed to use the standard mileage rate when reimbursing employees for business use of their personal vehicle.
Instead of reporting vehicle expenses on the business return, partners are allowed to record vehicle expenses using the standard mileage rate as an unreimbursed partner expense on Schedule E of their 1040 return. This is only allowed if no depreciation or actual expense relating to the vehicle was recorded on the business return.