(23 Feb 2020, 11:11 am)mb134 wrote B5TLs on the Coastliner, same as GNE are using on the X9/X10. 

Volvo chassis, though smaller engine than what is on offer from ADL. That GNE are trialling buses on the X9/X10 may indicate that they're looking into replacing the B5s on there within a couple of years - and the Transdev order announced the other day for E400s on The Witch Way and CityZap indicate that they're not too hot on the Volvo/Wright option. 

In fairness to Arriva they didn't buy on the cheap for the X93, with the B9TL likely the best option at the time. Equally ADL E400s, at least the later ones, have proved to be solid buses.

GNE confirmed that they are replacing the the B5s on the X9/X10 within the next year or two as the B5s just aren't suited to the motorway (which is the main part of the route), plus I believe the not so great reliability was also mentioned.
They're looking at either upgrading it to a coach type vehicle (hence the trials with the Panther LE) or they're seriously looking in to the Scania E400s.

From my personal experience, the B5s on the X9/X10 are absolutely horrendous, the engine is far too loud and the ride is awful.