A method for transmitting data in a packet-oriented communications network, in particular of a motor vehicle, with a guaranteed maximum transmission time for the data packets in the communications network, and to a user terminal for carrying out said method. According to the method, before the data transmission a specific quality of service is reserved by a reservation request from the sender of the data to the receiver of the data. The reservation request including the data rate of the data stream and the latency as parameters of the requested quality of service. Once the reservation request is confirmed, the requested quality of service for the communication link between the sender and the receiver is guaranteed in the network for the data stream. In addition, the quality of service for the data stream is adjusted by the sender on the basis of the topology of the communication network and/or the resources of the communication link.