^ It would be interesting to know how the decision to offer the ZHP package on coupes and convertibles came about.
It could be that they planned it from the start, phasing in the 2-doors, in typical fashion, a year after the sedans. Or, it may be that it was in reaction to customer demand. If their salespeople heard "But, why can't I order it on a 2-door?" often enough, that input is bound to eventually make its way up the chain.