If you notice incorrect values on mileage claims you will need to take a look at the rates on the mileage scheme by following the steps below.
Go to Setup and click Settings.
Click Module Settings and select Expenses Settings.
Click Mileage.
Click the relevant mileage scheme.
Click each vehicle type to see its settings.
Amend the mileage rate for each vehicle as needed. The value added for the mileage rate will then be multiplied by the number of miles when adding a mileage claim in order to calculate the value of the claim.