Are you sure? I thought Passions are at IV, not VI. Otherwise I missed two relaunches.
Edith: I think @kodiakblair refers to the series, not the number of strings
Ok, thought he'd refer stringwise...
All 6-strings ever made are Series III also the one advertised. This one is identical with mine, definitely Series III, build in the nineties.
I asked the shop for the serial no. for I then can identify the day when it's been made.
To my knowledge Series IV indeed is the latest. However there seems to be some confusion:
I also own a 2001 Passion 5-string which has different bridge than series III (i. e. mono rail) and a moderate electronics update (yet still parametric).
Some friends identified this one to be Series IV, but I would count it as an III-update version. It sounds a little different compared to the former III Series.
The later "official" Series IV is completely different in electronics, pick ups, has bold on instead of neck thru, has a modified body shape and after all unfortunately has more weight. Available as 4 and 5-string. I had one, but gave it back since I prefer the series III over the IV.
Since the Series IV also has gone thru some minor modifications (mono rail replaced by solid block bridge, new colors) some shops offered the modified Series as "Series V" in the past... but the main build still is Series IV. Bassdirect offers both version aside as "IV".