That clip is interesting. In Dublin we had buses with General Motors 6V71 two stroke engines which sounded very similar to that. However they were coupled to Allison three speed gearboxes, with a splitter on the second gear, creating a unique sound effect. To listen to them in action, similar to the bus in the clip, there are three or four different sounds running simultaneously, which would be nice to recreate in OMSI. Hopefully the way to do this will become clear. It might be possible, by observing how many sound recordings were used for the Berlin SD bus, and seeing how they are assembled in the program, to learn the best way to do it.
For example, I would like to use the sound recordings of the Voith gearbox on the Berlin bus, but mate them to a recording of a Cummins L10 engine. I hope that will be possible too.