Excess Mileage Charge
The excess mileage charge is the price of every kilometre you drive over the included allowance. It only exists on limited-mileage rentals; with unlimited mileage there is nothing to exceed.
The rate is set per kilometre and is usually higher than you might guess, because it is meant to discourage going over rather than to be a fair fuel-style cost. A few hundred extra kilometres can therefore add a surprising amount to the bill.
The figure is recorded by comparing the odometer at pickup and at return, so the photo you take of the dashboard at the start is useful evidence if a calculation looks off.
If you suspect you will exceed the allowance, it is often cheaper to switch to an unlimited-mileage rate before you set off than to pay the per-kilometre charges afterward.