US planemaker Boeing on Tuesday announced a commitment to sell 100 upgraded single-aisle 737 planes worth a combined $9.2 billion (7.5 billion euros) to leasing group GECAS. Boeing stressed that the deal was still to be finalised. \"Boeing announced today at the Farnborough International Airshow a commitment by GE Capital Aviation Services (GECAS), the commercial aircraft leasing and financing arm of General Electric, to purchase 75 737 MAX 8s and 25 Next-Generation 737-800s,\" said a statement issued to media at the British event. \"Boeing looks forward to working with GECAS to finalise the details of the agreement, at which time the airplanes will be posted to the Boeing Orders & Deliveries website as a firm order.\" Boeing\'s 737 MAX is an upgraded and more fuel-efficient version of the 737, the world\'s best-selling commercial airplane. The first 737 MAX is scheduled to be delivered in 2017, two years after the neo, which has been billed as a more fuel-efficient A320 thanks to engine upgrades. The 737-800 is meanwhile already in service. \"The 737 MAX is a perfect complement to our airplane portfolio,\" said GECAS chief executive Norman C.T. Liu. \"These new Next-Generation 737 and 737 MAX airplanes will continue our long-standing strategy of providing our customers the most fuel efficient, most capable airplanes with the lowest operating costs.\" The deal, once firmed, builds on Boeing\'s announcement on Monday that it had won a contract worth $7.2 billion for 75 of its short-haul 737 MAX jets from US group Air Lease Corporation. Boeing is seeking to steal a march over its European rival Airbus, which has enjoyed great success with orders for its upcoming A320neo. Despite its two huge orders at Farnborough, Boeing is still playing catch-up with Airbus in the market for upgraded single-aisle planes.