You should add different engine sounds for all the cars because sometimes when I play always hear the same sounds and it gets annoying. Like instead for the trucks having a car engine you could a proper truck engine.
Yeah it could be great if all the cars had different engine sounds . But there i an lua script for that .
http://www.beamng.com/threads/5005-...ipt-(update-08-12-13)?highlight=engine+sounds There you can find something interesting
I think the dev's mentioned there was a sound overhaul planned. And that these current sounds are just temporary.