US aircraft leasing group ILFC has ordered an extra 50 Airbus A320neo airliners with a catalogue price of $5.0 billion (3.7 billion euros), the two companies announced on the first day of the Paris Air Show on Monday. In 2011, ILFC had ordered 100 of the A320neo aircraft which are more fuel-efficient than the A320 series, widely used by low-cost airlines and on short-haul routes. The announcement was made by the head of ILFC, Henri Courpron, alongside the head of sales at European aircraft manufacturer Airbus, John Leahy. Leahy noted that ILFC was the biggest overall customer for Airbus planes, having ordered 769 aircraft of different types. The value given for the latest deal is a catalogue price, but the final prices at which deals on airliners are done is often lower than the list price. Courpron said that ILFC had not yet decided which type of engine should be used on the aircraft. The choice lay between engines made by Pratt and Whitney which belongs to the US United Technologies group, or by CFM which is a joint venture between Safran of France and US group General Electric. The aircraft would be delivered from 2015 to 2020, Courpron said.