1. A method for detecting the road condition for a vehicle, comprising: detecting, by a vehicle sensor device, a vehicle dynamics variable describing the dynamics of the motor vehicle while the vehicle is being driven; performing, by a computing device of the vehicle having at least one processor, a frequency analysis of the vehicle dynamics variable, the frequency analysis comprising a first filtering operation, an absolute value calculation operation, and a second filtering operation separate from the first filtering operation; and ascertaining, by the at least one processor, as a function of the frequency analysis of the vehicle dynamics variable, a road condition variable describing the instantaneous roughness of the roadway surface.