That's a bit of a surprise, can you enlighten us any further? All cars are powered so it ought to be able to move, could it be something to do with tilt not having another car to talk to?
And having recently suffered journeys on overcrowded 2-car 150s (and a 4-car Voyager) in Cornwall I would suggest or propose that they could be used there, maybe with a new intermediate car to add capacity.
I think it is that the end cars don't have air compressors, but I may be wrong.