Loco Northen Class 158

A diesel multiple unit operated by northern go from Peterborough to Doncaster in train sim world 6:

 

Northern don't go to Peterborough.

 

It'd only be AI on that route anyway, at Doncaster and Retford (on the low level so you'd barely notice it, plus that's mostly 195s anyway)

Could go on Manchester Airport I suppose but the fact they use the scotrail one suggests there's no plans for a northern one anyway