If your company pays for all your fuel used by your company car and you do not identify and pay back the personal mileage element, then there is a taxable fuel benefit as well as your car benefit.
The car fuel benefit is based on a set figure £24,100 (2019/20) x CO2 emissions percentage for your company car. To calculate the CO2 emissions percentage use this table.
So in this example the car fuel benefit is £24,100 x 27% = £6,507 taxable benefit.
Therefore the director will pay personal tax on this amount, if he is higher rate tax payer, this will be £6,507 x 40% = £2,1602.80.