I believe the extra charge for the package was around $15k - but am not positive
This was for the 360hp motor, tranny and aluminum wheels.
I thin 9 - 11 mpg is about normal for the Berkshire. Really +/ a 1 or 2 mpg is not going to matter one way or another. How you drive is prba le going to influence this more than any other factor.
As for the comment on the power helping when loosing momentum - I woul stress that big RVs are all about momentum!! One thing I find annoying is getting cut off by a allow moving car going up hill and having to slow way down. You just can't make up the speed..
2011 Berkshire 390BH-60
Cummins ISB 360hp/800ft-lbs DEF