You may deduct car washes if you take actual expenses. The only additional expenses allowed with standard miles are below.
Actual Expenses - To use the actual expense method, you must determine what it actually costs to operate the car for the portion of the overall use of the car that's business use. Include gas, oil, repairs, tires, insurance, registration fees, licenses, and depreciation (or lease payments) attributable to the portion of the total miles driven that are business miles.
Note:
Other car expenses for parking fees and tolls attributable to business use are separately deductible, whether you use the standard mileage rate or actual expenses.
