In this paper, we present examples of DInSAR-based measurement of surface displacements using a novel compact L-band SAR system that can be mounted on mobile mapping platforms such as a UAV or a car. The good DInSAR system performance is demonstrated and, particularly, we also show a use case in which a car-borne system setup is employed to map surface displacements of a fast-moving landslide and the surrounding area in Switzerland. Our results show that car-borne and UAV-borne interferometric displacement measurements at L-band are feasible with high quality over various natural terrain. This novel compact DInSAR system for agile platforms complements existing terrestrial, airborne, and space-borne radar interferometry systems in terms of its new combination of (1) radar wavelength (sensitivity to displacement/decorrelation properties), (2) spatial resolution, (3) (near-) terrestrial observation geometry, and (4) mobile mapping capability.