No that's not true. All you need is a signed form from employer that your vehicle is required for the position and you can write off the portion of expenses that the vehicle is used for your job, as a regular employee.
when they are paying you straight mileage? Pretty sure as an employee, you can't get reimbursed a tax free mileage expense and then write off vehicle expenses. But, you can do pretty much anything you want until you get caught.
