reimbursement for mileage traveled with your personal vehicle isn't required of the employer, if they dont pay mileage, its up to you to claim it on YOUR taxes.
Most business pay it because thats a 100% write off.

 

If you were to get fired due to reporting a conflict in payroll, you'll have an even bigger case! Once the state/feds get involved, your employer had better be doing every thing by the book. Good luck! Drop a dime to the authorities.....it will be in your best interest in the long run. If nothing else, they will advise you of what is right/wrong, and what your rights are.