There are no hidden costs with us. No registration fee, no refuelling, no parking fees; you only pay for the kilometers actually driven (0,89€ / 1,19€) and for the minutes in which you block the vehicle (0,09€ / 0,29€). (For example, when you make a reservation or make a short stop at Rewe.)
As a rookie (driver's license for less than 12 months) you belong to a risk group and therefore pay a little more. You can find an overview of the exact prices here.