Click the image to listen to the sound. I would put the video here, but videos make the projects lag or even crash, so I just put the audio. But anyways, I've been noticing that this bus has a realistic axle noise when driving it in Rigs of Rods (if you don't know what the axle noise is, that's the low pitch sound going into high pitch. You'll hear it on this bus when the transmission changes to 2nd gear). I've rode a bus with a similar axle sound to this (but it was a 1st Gen CE, not a 2nd Gen CE) and it sounds really good! The sound reminds me of the axle sound this bus is making in this video: https://www.youtube.com/watch?v=DeyQ_hp7ZDI Do you hear the similarities in the axle noises? Different engines though.
Idk exactly where the engine sounds originally came from since I didn't make/mod this bus, but I give credit to wherever they came from.