A key metric for fuel efficiency is seat miles per gallon (SMPG), which takes into account both passenger capacity and distance flown. The Rolls-Royce Trent XWB achieves about 25-35% greater fuel efficiency than the Trent 900 over similar distances. This advantage comes from its advanced three-shaft design featuring thermal and aerodynamic improvements as well as new materials that withstand higher temperatures.
The difference in efficiency is also influenced by aircraft design: the A380 is heavier than the A350 and has four engines compared to two on the latter. More engines typically mean higher fuel burn due to increased drag.
The Airbus A380 entered service in October 2007 but ceased production in 2021 after a total of 251 deliveries. Nearly 200 remain operational today as airlines like Emirates continue to invest in retrofitting their fleets for extended use until around 2040.
The more modern Airbus A350 entered service in January 2015. Over 600 have been delivered globally so far. In North America, Delta Air Lines leads operations of this model; Singapore Airlines operates an ultra-long-range version connecting Asia to cities such as New York and Los Angeles.
New orders continue for the A350 powered by Trent XWB engines. Riyadh Air’s CFO Adam Boukadida said: "The growth of Riyadh Air is of critical importance to the development of Saudi Arabia as an aviation hub, and selecting world-class companies like Rolls-Royce to power our future Airbus large wide-body fleet ensures we have the right partners in place to achieve our ambitions," he said. "This MoU for 50 Rolls-Royce Trent XWB-97 engines to power our fleet of Airbus A350-1000 aircraft is hugely significant as it brings us closer to realizing our long-term vision of enhanced connectivity for Riyadh. Our goal is to deliver an unrivalled guest experience, linked to a world-class network and provide our guests with unlimited options to fly direct to major global cities.”
Comparing these engines against others on the market shows that while Boeing’s GE90-powered 777-300ER achieves about 80-90 SMPG—similar to or slightly better than an A380—it remains behind the efficiency levels seen on an A350 equipped with a Trent XWB engine.
Looking ahead, future models like Boeing’s upcoming GE9X-powered 777X could set new benchmarks for efficiency at an estimated 100-110 SMPG once it enters service (expected no earlier than 2026).
Currently, however, industry data indicates that the Rolls-Royce Trent XWB delivers approximately 95-105 seat miles per gallon—outperforming both its predecessor (Trent 900 at roughly 74-80 SMPG) and other existing major commercial jet engines.
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