One problem related to ignition coils failure has been reported for the 2005 Porsche 911 Carrera. The most recently reported issues are listed below.
Engine ignition coils fail due to cracks and corrosion. The car will not exceed @ 20 mph, thus putting the occupants at risk. This is a problem other Porsche owners have also experienced. Porsche replaced 6 coils on my vehicle all identical to the original units which failed. Thus the vehicle will again fail in traffic.