Or reimbursement for mileage. Businesses can take this as a tax write-off (i.e. no payroll taxes) from the IRS [0]. My father used to get reimbursed for mileage from his work at the IRS rate, which accounts for things such as reduced car value, gasoline and maintenance costs, but is actually quite generous. The reimbursement rate was high enough that he actually
made money from it, since it exceeded the costs of gas, increased maintenance and depreciation. That said, if you drive a ferrari which depreciates quickly and guzzles lots of gas, the calculus is going to be different.
[0] https://www.ifebp.org/news/regulatoryupdates/Pages/2019-irs-...