The IRS deduction is premised on the operating costs of a vehicle, not solely the gas or diesel it burns. You cannot compare diesel and gas used in the machine on the back of a truck, to the gas or diesel used IN the truck. The IRS deduction will not float for the equipment fuel usage scenario. If you are to compare apples to apples, add in license, registration, insurance and maintenance...and then see if you are coming out ahead. You won't be. If your company is paying for your truck, vis a vis car payments, gas credit card, paying the insurance bill, etc., then you cannot also write off a deduction. The simplest method is to have the company pay all vehicle related expenses. Now if the question refers to reimbursing an employee to use his own vehicle, then he must bear the daily expense of fuel as well as all insurance and maintenance, and then you pay him $.365. The IRS, hard as it may be to believe, is not in the business of, nor interested in, giving the taxpayer a way to "make money" off deductions. If they give you an "allowance" of .365, it generally will fall way short of what is really required.