In response to MB134 from March:

I think that although B9s on the X18 would be great, the current E400s seem to cope fine. Also, had a ride on 7508 (original X31 / X32 batch) today from Newcastle to Bedlington Front St on the X22 and it seemed fine.

Hopefully, none of the 09 plate and above E400s should end up in the same state as the 57 plates particularly the original 308 batch (7501-7506). Got to remember that the B9s are also heavy duty and although the fuel economy is only slightly less than an E400 (which still adds up), the cost of maintaining Volvos when they go wrong in the long term is also more. These two factors alone are crucial for rural Northumberland routes due to recent cuts etc.