(23 Dec 2013, 12:59 am)Kuyoyo wrote No, notice that the B9TLs on the X9/X10 have been proving unreliable in the last few months and they are only 16 months old! The DB300s have proved themselves more than capable on the fast express between Blyth and Newcastle as well as on the X1/X2. And actually, Cummins engines are actually quite decent engines, just depends how they are set up. Also you fail to realise as of Euro6, the Volvo decker is the B5TL, so no 9 litre engine anymore (and funny enough, it was the operators that requests the 5 litre engine, Volvo were originally going for the B8TL to go with the B8RLE and the B8R). As do Scania's deckers! you do realises they can be ordered with 3 different BHP ratings (Stagecoach have been ordering the lowest one, the 230, while there is also the 270 and the 310 options).
As for vehicle allocation, it's the same as everyone else - the newest vehicles are used on the most profitable routes, which are the ones that can justify them.
The DB300s aren't as reliable as you'd ideally like but they do ok on express routes, they are limited at 50mph though which isn't ideal. Many have undergone expensive engine rebuilds at 2-3 years old! Having said that, the B9s on X9/X10 are starting to have issues too, the 0710 X10 from Middlesbrough hasn't run the morning because it broke down coming south. They're both decent vehicles but not designed for the purpose they're used on.