tuna - I think that your comparison is missing a few variables. The G550 has to fly slower (M .80) than the G600 to achieve that 6700nm. The G600 is pushing a significantly larger airframe through the air, at M .85 while still having a respectable range of 6200nm (as advertised). The G600 will achieve this having the same MGTOW as the G550. If flown at the same speeds you can bet that the ranges would be about the same. The G600 meets the desired goal of having the larger cabin that Gulfstream customers want, pushing that larger airframe through the air (requiring more power to achieve) with more efficient engines and 2500 pounds less fuel capacity than the G550...while doing so at much higher speeds.
The G450 and G550 are great airplanes. But Gulfstream customers wanted newer technology, more speed, more cabin, with greater efficiency. The new G500 and G600 are those airplanes. They will fit their niches well along side the G650/ER.
Last edited by AZAV8R; 21st Aug 2015 at 06:54.