I use my vehicle for my job and deduct my mileage, however my refund only reflects the difference I paid in on taxes. Why am I not getting more for the 27K+ miles I drove?

Under the new tax laws employee related job expenses are no longer deductible. 

"You can no longer claim a deduction for unreimbursed employee expenses unless you fall into one of the following categories of employment, or have certain qualified educator expenses.