International Airlines Group, the parent of Iberia Airlines (which is also the operator of the last production A340 built), is overhauling its A340-600s for continued service for the foreseeable future, while it is retiring its A340-300s. The IAG overhaul featured improved conditions and furnishings in the business and economy classes; the business-class capacity was raised slightly while not changing the type's overall operating cost. Lufthansa, which operates both Airbus A340-300s and -600s, concluded that, while it is not possible to make the A340 more fuel efficient, it can respond to increased interest in business-class services by replacing first-class seats with more business-class seats to increase revenue.