This paper addresses multi-dimensional Ground Moving Target Indication (GMTI) using a multi-channel Wide Band (WB) Synthetic Aperture Radar (SAR) system. For limited time intervals the target acceleration is so small that target motion can be related to two ground and two speed coordinates. However, four other dimensions are used in WB SAR GMTI processing during the detection phase: azimuth, range, bearing, and the relative speed between the object and the SAR platform. In the detection phase, blind hypotheses are used, and the discretization steps between the hypotheses are a trade-off between the number of hypotheses tested and detectability. As the integration angle increases, the bandwidth increases and the therefore the number of tests increases. In this paper we discuss the discretization step in all four dimensions for moving target detection, and analyze the step size in particular in the most critical domain, the relative speed. The analysis is made on CARABAS II data.