Unfortunately, if you are an employee (Paid with a W2 not a 1099), beginning with your 2018 Tax Return, you can no longer deduct employee related expenses.
The Tax Cuts and Jobs Act (TCJA) that was signed into law in December of 2017 eliminated all "Miscellaneous Itemized Deductions" formerly allowable on your Schedule A. This includes all for "unreimbursed employee expenses" including business mileage.
For more information, please check out this TurboTax FAQ: How Will New Tax Legislation Affect My 2018 Tax Return?
