If you prefer to explore the city or just to get around in a car, you are most likely in a need of a rent car. In Nuremberg are many companies operating on the market, but only a few of them are able to communicate with you in English.
Beside your passport and your driving license you are definitely going to need a credit/debit card to rent a car. The provider is going to freeze the rent and security amount on it.
The rent fee should cover also the insurance and a full petrol tank which you need to refill before giving back.