In this paper, we introduce a millimeter wave (mmWave) channel sounder design to enable dynamic vehicle-to-vehicle propagation measurements such as short range train-to-train and different car platooning scenarios. The RUSK-DLR channel sounder has been extended with mmWave frontends to up- and down-convert intermediate signals. This combination is enabling us to perform accurate dynamic mmWave propagation measurements in a dynamic manner. The design of the frontends and the evaluation through lab tests and outdoor measurements are described. Outdoor measurements covered static and dynamic scenarios. Measurements at ranges up to 110 m were performed. We could accurately record channel impulse responses, phase measurements and delay information in the different scenarios.