Where cities have pollution restrictions, for example, a driver could elect to drive purely on the battery, or to switch to that quieter mode in a school zone.
That confidence was in recovery mode as the euro zone debt crisis receded from front pages worldwide, but the European bank stress tests are creating anxiety for some investors.
So, despite the improvement in the Japan situation on Friday and the declaration of a no-fly zone over Libya, traders decided to avoid the potential headline risk and went back to risk-off mode into the close.