With a single power unit, they would be restricted to maybe 90/95mph, I think, but the bigger question is how do you get around the forthcoming legislative requirements for accessibility, which are driving the removal from service of Britain’s, and the world’s, best DMU?They could have used mk3 DVTs with shortform HST sets to create some comfortable long distance/cross country trains, otherwise: power car, 3 x TSO, buffet/restaurant TF, DVT.