In this paper, we explore the delivery of fast breathing interventions in a driving context, given the proven effects of high-paced breathing on autonomic arousal. Through in-lab simulator studies, we demonstrate the feasibility of using haptic guidance to increase breathing rate, intensity, and heart rate as well as subjective perceptions of alertness and focus. We also assess usability and user receptivity towards the approach across various simulated driving scenarios (highway, city), times of day (day, night), and traffic levels (low, heavy, fast). In doing so, we outline specific use cases where fast breathing interventions are more or less appropriate and beneficial (e.g., during long, monotonous drives on the highway or at night vs. complex or tense driving scenarios), and we offer fertile future directions for the continued development of breathing systems for health and well-being.