Nürburgring organizers and the police in nearby Adenau confirmed that a car had come off the track during a long-distance race and flew over barriers into the spectators.
The cause of the accident was not immediately clear.
The race was immediately ended and not restarted.
Authorities did not say exactly how many people were hurt in the crash.
They were brought to nearby hospitals in the Eifel region of Rhineland-Palatinate in western Germany.
The one casualty was not immediately killed, but died of his injuries in the racetrack's medical centre.
Legendary Formula One driver Jackie Stewart called the 26-kilometre Nürburgring "Green Hell" for its fiendish complexity.
Its North Loop alone features more than 300 metres of elevation changes over its 21 kilometres.
Deaths during races are rare, but there are more often accidents, sometimes fatal ones, during public sessions on the track.