A method for adaptively controlling a vehicle speed in a vehicle includes establishing a reference speed; and activating an engine and/or brakes and/or a transmission of the vehicle by a speed-control system as a function of a set vehicle speed and/or a set vehicle retardation for fuel-saving adaptation of the currently existing vehicle speed to the reference speed. The set vehicle speed and/or the set vehicle retardation for a current driving-dynamics situation of the vehicle defined by driving-dynamics vehicle parameters is/are determined as a function of at least one computation coefficient. The at least one computation coefficient is provided by an external arithmetic unit outside the vehicle as a function of the currently existing driving-dynamics vehicle parameters and also as a function of currently existing route information for a route segment situated ahead. The route segment situated ahead is established on the basis of the currently existing driving-dynamics vehicle parameters.