Yes. You will get 100 miles free per night with your rental. You will then pay $.25-35 per mile depending if you prepay the mileage or not.
So if you rent for 2 nights you get 200 miles free. If you drive 300 miles, there is an excess of 100 miles.
100 miles x $.35 = $35
Excess milage fees are calculated and charged upon your return of the rental.