If you drive your Fiero down a road, just following the speed limit, maybe 35 MPH, and the rear wheels intermittently hit bumps, the Fiero will briefly self-steer. It corrects itself rapidly, so some people automatically make small compensatory steering adjustments. Yes, if you push your Fiero hard through the turns, it will also self-steer, which can be disconcerting. Depending on the banking, the rear wheels can steer in opposite directions. Alternatively, the rear end can cause oversteer or understeer, going through turns, depending on braking or acceleration. If you know what is happening and why, you can adjust.