When it comes to fuel efficiency and carbon emissions, motorcoaches are the cleanest mode of transportation, according to a new report commissioned by the American Bus Association (ABA) and conducted by M.J. Bradley and Associates.

The study compares motorcoaches to 11 other modes, including intercity rail, transit buses, commuter rail, domestic air travel and private automobiles.

Motorcoaches average nearly 240 passenger miles per gallon, while intercity rail averages 85, commuter rail 90, transit buses 70, domestic air travel 55 and single-occupant cars 28.

In terms of carbon dioxide emissions, motorcoaches are more than twice as efficient as the next closest mode, more than three times as efficient as Amtrak and eight times more efficient than a single-occupant car.

The report shows that, in addition to motorcoach transportation’s inherent advantages in pricing, flexibility and on-board amenities, travelers can choose motorcoaches based on sustainability as well.

"Many in Washington, D.C., believe that, in order to reduce congestion while creating green transportation options, government must provide massive ongoing taxpayer support," said ABA President/CEO Peter Pantuso. "As the data shows, America's privately operated motorcoach fleet is the greenest form of transportation. It provided nearly 640 million passenger trips in 2012 while doing so with little to no taxpayer subsidy. Our industry is proud of our success, and we hope that, as Congress considers the next transportation authorization bill, they consider what it truly means to be sustainable."

To view the full report, click here.