The Boeing 787 Dreamliner is a long range, mid-sized, wide-body, twin-engine jet airliner developed by Boeing Commercial Airplanes. It seats 210 to 330 passengers, depending on variant. Boeing states that it is the company's most fuel-efficient airliner and the world's first major airliner to use composite materials for most of its construction. The 787 consumes 20% less fuel than the similarly-sized Boeing 767. Its development and production has involved a large-scale collaboration with numerous suppliers.
7,650 to 8,200 nautical miles (14,200 to 15,200 kilometers)
Total Cargo Volume:
4,400 cubic feet
Maximum Takeoff Weight:
502,500 pounds (227,930 kilograms)
in my view, it seems that the plane was badly modeled here, sources taken from the company's Web site, the 787-8 was specifically made to replace the existing market planes (767, 777), not the airlines get to discussing what is the best choice
Paraphrased from a post I made a year ago:
You can look at other official Boeing figures to get a rough idea of fuel economy and can see that the "20% figure" that PR throws around around just doesn't jive up with reality. Carrying roughly (give or take a few) pax, the 787 has a fuel tank about 38% larger than a 764ER; and a range of about 44% more. If indeed the 787 got "20% better fuel economy" it should be able to get a LOT further given it's fuel tank is so much larger. It should easily go 9100+NM if it was indeed burning 20% less fuel for every pax onboard with as much fuel as it's got, but it can't even come close to that. And the reason is because, fully-laden, a 787 weighs 20% more than a 764ER.
Given other Boeing information, I would say that the real-life (rather than PR-speak) fuel economy difference between the 787-8 and the 767-400ER is probably in the 5-10% range on the per-passenger level, and that's at best.
Here's a link to a site ( http://www.lissys.demon.co.uk/samp1/index.html ) that did full modeling of the 787-8 using Piano-X, a tool used by airframe and engine manufacturers including Boeing, and they came up with an estimated fuel economy of 11402 lb/hr at cruise with the GEnx -- almost spot-on what Sami's got here.
Long and short -- the 787 is
20% more fuel-efficient than a 767. But one must consider that it's a very heavy plane made to carry large amounts of fuel and cargo. Being more fuel-efficient doesn't necessarily mean burning less fuel, it means that you can move the same amount of weight
further. Or, in the case of the 787 -- more weight without burning more fuel. You get into the same 'issues' when comparing trains with semi-trucks -- a locomotive is more efficient
but it's really burning a LOT more fuel than a truck is.