At this? Gen III 2010+ Prius Main Forum. Eek!!!! Roman numerals!!! Witches!!! Witches!!! So according to PriusChat Forum you have a Gen III/Model 2 Wonder where they got the roman numeral thing for the I, II and III generation Prius? I wouldn't get too hung up about it. As you long as people know what you mean, Prius III/3 seems clear enough even if it's a dog whistle to some.