The following from a reputable site :
Irn-Bru 32 is a brand extension to the Irn-Bru range, and is the first time Barr themselves have marketed an Irn-Bru variation in the functional energy market. Whilst Iron-brew flavoured energy drinks have been available for a while, either in non-alcoholic or alcoholic variations, these beverages have usually been at the value end of the marketing spectrum usually coming in litre bottles. On the other hand, Irn-Bru 32 will be marketed at the top end of the category against other energy drinks such as Red Bull, V and Red Devil. Its name is claimed to come from the 32 secret ingredients of Irn-Bru.[4], although this could also be explained by the fact that the drink contains caffeine in the concentration 32mg/100ml
So there you go Mr Black Knight