In 2020, the standard business mileage rate for use of a car is 57.5 cents/mile, down from 58 cents/mile in 2019.

Your staff should be reimbursed for any job-related mileage driven in their personal vehicles. (Driving to and from work doesn't count.) An accountable reimbursement plan keeps these payments nontaxable. This is especially important now that employees can no longer deduct unreimbursed business expenses on their taxes.