One problem related to ignition coils failure has been reported for the 2010 Toyota Prius. The most recently reported issues are listed below.
Water leaking from engine cowel getting into ignition coils which is causing engine to shudder and stop sometimes too. Seems to be a known Toyota issue yet not being rectified by manufacturer. Seals seem to allow water to get into the ignition coils hence the issue. Vehicle is stationary when first observed then shuddering and misfiring occurring as vehicle is being driven also leading to loss of power as its being driven which is quite dangerous on highways.