Exactly! Thank you, Hope.

You typically use the standard mileage allowance rate to reimburse employees, so that you don't support inequitable treatment by who drives which sort, type, or condition of vehicle and incurs what level of costs. Also, you cannot easily repay actuals for business use of a POV (personally owned vehicle) when that gas tank full might have been used to drive kids to school, go hunting, and also pick up a new tire for the tractor at a job site.

By using that standard mileage allowance rate, you have no need for proof of details of expenses. That's in parallel with an accountable plan for similar costs incurred, such as per diem. But, if you own more than 10 percent of the corporate entity, you may not use the daily per diem allowance that covers lodging, meals, and incidentals.

On the other hand, the actual costs to own and operate a company-owned vehicle are fairly easy to determine.

"allowed to deduct actual vehicle expenses (to the extent of business use)"

Personal use of a company-owned vehicle is a taxable fringe benefit, charged through payroll. The company tracks all costs, but their expenses are reduced by amounts charged to employees as a fringe benefit. Example: You run a fleet of trucks for a construction firm, that also are available to use personally during hunting season = taxable fringe benefit.

And none of this helps with what the OP asked. There is a 2% rule related to health insurance premiums...