Flying fewer bags is helping to save the earth, that’s at least according to Spirit Airlines, which recently crowned itself the greenest major U.S. airline.

The self-ranking is based on its on-going measures to reduce fuel consumption and become more eco-conscious, the Miramar-based low-cost carrier said Wednesday, in a statement.

Among them, its “Bring Less, Pay Less” baggage policy, which allows passengers one free small personal item onboard, but also charges up to $45 for bags stored in overhead bins.

That policy has led to fewer bags on its planes, which in turn has resulted in fuel savings of nearly 6 million gallons in the past year.

“That’s not only a major cost savings that we can pass along to our customers by way of low fares, but also a major positive impact on the environment thanks to our customers,” Spirit’s Chief Marketing Office Barry Biffle said.

Other efforts include its transition to, and acquisition of, new and more fuel-efficient aircraft.

“We are proud of the fact that we burn far less fuel per passenger than our competitors,” Biffle said.

Spirit said its A320 aircraft provide 89.4 passenger miles per gallon, which reflects the distance it can fly a passenger on a gallon of jet fuel. That compares with JetBlue Airways’ 75.5 mpg (A320), Southwest Airlines’ 68.8 mpg (Boeing 737) and American Airlines’ 52.9 mpg (MD-80).

An “eco-friendly seating configuration,” which essentially means Spirit packed more seats on its planes and trimmed the leg room, has also helped its green efforts.

“That’s why we get such good gas mileage per customer … plus our young Airbus fleet is much more fuel-efficient overall than airlines with older planes,” spokeswoman Misty Pinson said Thursday.

Spirit’s reputation for unconventional and often controversial marketing may make consumers dismiss these claims, but the airline takes its green efforts seriously, Pinson said.

“These are very real and quantitative eco-conscious measures we have taken that are both environmentally-friendly and allow us to offer the ultra-low fares our customers love.”

Still Spirit’s claims may be surprising since it hasn’t been a frontrunner in any recent industry green rankings, but size may be the reason.

It wasn’t included in two recent green studies because it wasn’t considered among the top 20 U.S. or global airlines.

In May, Greenopia, an online directory of green businesses and organizations ranked Virgin America, Alaska Airlines, United, JetBlue and Delta as the greenest U.S. airlines. Others making the list were US Airways, Southwest, Air Canada and American.

The carriers were rated on fuel conservation practices, alternative fuel research, recycling efforts, use of organic, local and fair trade food, green building design and carbon offsets.

In a 2011 Brighter Planet study of the best and worst airlines for energy efficiency, Continental, JetBlue, Frontier, United and Alaska scored top marks in the U.S. domestic market.

This report examined key efficiency drivers that affect fliers’ carbon and energy footprint, including aircraft type, load factor, seating density and distance.

“By our measures the average U.S. flight is 20 percent more efficient than it was 10 years ago, mainly due to more efficient aircraft models and fewer empty seats,” said Robbie Adler, director of business development and strategic partnerships at Brighter Planet. “Thanks to this improvement total domestic aviation emissions have declined slightly despite an increase in passenger volume.”

(c)2012 the Sun Sentinel (Fort Lauderdale, Fla.). Distributed by MCT Information Services.