And Ilyushin and Tupelov, the two primary manufacturers of airliners, are developing longer-range, more fuel-efficient jets that they hope to sell to Western airlines.

Musk has described himself as a workaholic who routinely invests 100 hours per week running Tesla Motors and SpaceX, often flying in a fuel-efficient corporate jet.

The Japanese automobile manufacturer said yesterday that it would build a fuel-efficient jet, following in the footsteps of a long line of car companies that have tried their hand at aviation.

It announced a highly fuel-efficient jet in the early 70's called the 7J7, only to cancel the program a few years later when oil prices dropped.

While Airbus has opened a sizable lead over Boeing in the total aircraft market, it risks losing ground in the midsize segment, where Boeing has booked 266 orders for its new fuel-efficient jet, the 787.

The 7J7 was supposed to be an extremely fuel-efficient jet powered by an eggbeater-type engine called a propfan.

Air France has supplied CSA, the national airline, with fuel-efficient jets and credibility with travel agents.

"It is a very quiet and fuel-efficient jet," said Kristie Kerr, a spokeswoman for Southwest.

The star of the show was Airbus's A320neo, with the fuel-efficient jet racking up 667 contracts or commitments.

On Monday, Korean Air Lines announced an order for 10 787's, a midsize, fuel-efficient jet dubbed the Dreamliner.