I made a report of this but over a year ago (version 4.09, not a new bug), with no reply. Hope this gets fixed, as currently the G4M indeed doesn't have the range it should.
http://forum.1cpublishing.eu/showpos...&postcount=233
Note: I used a specific fuel consumption of 0,25 kg/hp/h which is my estimate for a WWII piston engine.
Betty's ingame range is about 1/3 of the real figure. One could do a similar test (with lower fuel load in order to not go crazy) with proper cruise settings, but my calculations alone should prove that something is wrong. Either it's the amount of fuel, or consumption or both.