I don't have a general good FPS at all but it does depend on my bus.
C400R on most maps gives me between 5 - 20 fps (23 at very best)
Gemini 1 or Citaro UK FL gives me around 15 - 20 fps on average.
My most laggy maps are BOTW Legacy and Scunthorpe, I get some serious bus jumping and I just quit the game. Driving around on Hertfordshire, BoTW 2.9, Yorkshire V2, Sutton Coldfield and Cotterell is nice but I have to keep most of the map running during the evening (game time) to match low PC performance.