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One potential cause of vibration and noise in an automobile results from rotational irregularities of the engine due to changes in the torque which can be alternatively resistive and active during an engine cycle. This paper presents an approach to measure this intracyclic speed phenomena and analyze its influence on the noise behavior of an automobile and its rotating components. The measurement is derived from high frequency sampling of an RPM signal. The influence of the number of teeth, RPM range and sampling methods (fixed frequency versus synchronous sampling) is discussed, highlighting the need for a high sampling rate measurement. The analysis of rotational irregularities are processed by the same order tracking methods as used for vibration and noise order analysis. This permits a single analysis approach to understand the interaction between intra-cyclic speed variations and traditional rotating machinery studies.