If you drive an employer car to the grocery store, the IRS treats that as a taxable fringe benefit. One valuation method is the cents-per-mile rule: personal miles × the IRS standard rate (70 cents in 2025), if the vehicle qualifies.
When the rule is available
The car must be regularly used in the employer’s business and its fair market value must sit under the published cents-per-mile cap. Above that cap, payroll usually uses the lease-value rule instead.
Commuting is personal
Home-to-work in a company vehicle is generally personal use, even if you take calls on the way. Estimate the fringe with the company vehicle calculator. This is not UK Benefit in Kind — there is no list-price percentage table.