Just watched Bullitt on one of the HD cable channels yesterday and spotted two P-cars:
http://www.imcdb.org/vehicle_30063-Porsche-356-A-Speedster-1956.html
and
http://www.imcdb.org/vehicle_2528-Porsche-356-C-Cabriolet-T6-1964.html
Looks like there was one more I didn't catch (although in my defense it looks like it made its appearance during the car chase scene):
http://www.imcdb.org/vehicle_165281-Porsche-356-B-Coupe-T6-1962.html