That's more to do with E200 and E400. That said, I believe a Euro-5 standard ISL engine is on offer, but it's a matter of anyone want to take it (yet).
Technologically though, Euro 5 is not such as hike from Euro 4. For Volvo, Cummins and Evobus, who uses SCR technology in particular, the upgrade is supposedly simple enough. That fact that in Britain at least, there have been a considerable number of Euro 5 standard Citaros and B7RLEs for a year or so really speak for itself.
