A control device for a compressed air preparation device of a vehicle outputs output signals for adjusting feed phases and regeneration phases of the compressed air preparation device. A compressor feeds compressed air via an air dryer having a desiccant into a compressed air reservoir in a feed phase, and compressed air is passed out of the compressed air reservoir through the air dryer for drying the desiccant in a regeneration phase. The control device adjusts the regeneration phases depending on a current or future engine load and/or a current or future consumption of compressed air by the vehicle. In overrun phases, the desiccant can be excessively dried to a low moisture level in order to save fuel in later travel segments. Route-optimized regeneration of the desiccant as a function of engine load and/or utilization phases can also be effected.