A process and system are provided for determining fuel consumption of a motor vehicle. A first mean fuel consumption, which cannot be reset under a user's influence, is determined. A second mean fuel consumption, which can be reset under a user's influence, is determined as a function of several measured values. A third mean fuel consumption is determined as follows: (a) at the beginning of a predefined time period, which starts with a resetting of the second mean fuel consumption, the third mean fuel consumption is set to be equal to the first mean fuel consumption; (b) between the beginning and the end of the predefined time period, the third mean fuel consumption is set to be a weighted mean of the first mean fuel consumption and the second mean fuel consumption; and, (c) starting at an end of the predefined time period, the third mean fuel consumption is set to be equal to the second mean fuel consumption. A signal indicative of the third mean fuel consumption is provided.