I discuss the dynamics of two-dimensional, self-propelled microswimmers whose center of rotation may not coincide with the center of mass. This geometry, besides being more realistic, requires a more refined modeling of the swimmer dynamics, and largely impacts their diffusivity.

Moreover, if constrained along a specific orientation of their rigid bodies, such swimmers behave like non-holonomic particles (sleds) exhibiting orientation-dependent dynamical instabilities. In the presence of fluctuations, their motion alternates between runs and tumbles, resembling the observed motion of, e.g., E. coli. When adding a self-propelling force, this mechanism leads to a strong suppression of diffusion controlling the spatial range of swimmers’ movement.