The brake system is a critical safety component in motor vehicles. Advances in the electrification of the powertrain and the rise of autonomous driving technologies are significantly impacting the brake system, which allows innovative approaches and necessitating the development of new brake concepts and new deceleration strategies. A major technological advance is the decoupling of the driver from the brake system through Brake-by-wire technology. A crucial attribute of Brake-by-wire systems is the attainment of a concept-independent deceleration behavior. To establish a consistent and brand-specific deceleration behavior in the early development phase, objective metrics and perceptual thresholds are required to describe the desired subjective braking behavior. Moreover, objective metrics are indispensable for the virtual phase of the vehicle development process. This article focuses on deceleration from a straight-ahead drive. To identify objective metrics and perceptual thresholds, a testing procedure and a set of potentially robust metrics are first defined based on literature, expert knowledge, and specific driving characteristics related to deceleration. Suitable metrics and perceptual thresholds are then derived from a subjective evaluation study, objective measurements, and subsequent correlation analysis. As a result, objective metrics for steady-state deceleration, deceleration build-up time and deceleration built-up were established. A subsequent benchmark of current vehicles demonstrates the applicability of the identified criteria.