frank, nothing's different from AH.
It's just the pitch of the engine sound is linked with the RPM, and the overall volume of it is linked with the throttle now. So, when you fly level and close the throttle, you'll see the engine revving down both visually, and audibly, at the same time going almost silent(which, I think is a bit overdone).
...
The new fuel burn factor effects the flight time of the plane, not the plane performance, so u don't have to worry about that. As a rule of thumb I think about 70~80% throttle with 1800~2000RPM is the best for fuel conservation in most planes - we'll probably need to find out the correct historical data for those too.