. >> this cart is kind ofheavy. this one is noticeably lighter. >> reporter: these new beverage carts are 27 pounds. that's about half the weight of the old 50-pound carts. these new cargo containers are about 80 pounds lighter which will save 2 million gallons of fuel a year and stopping duty-free sales saved united another 1.4 mil that is a combined savings of $n milliogan. all of these efforts, what does that mean as a bottom line for the airline? how much fuel does that save you? >> we improved our efficiency over 30%. that's through the changes that we're making on the interior of the cabin, the changes on the exterior of the craft as well as new aircraft we're purchasing. >> reporter: changes that have saved unite the well over $2 billion. other airlines are also pinching pounds. southwest is rolling out slim line seats in its new 737 max fleet. they're lighter and take up less space. the low fare carrier saved 148,000 gallons of fuel by changing how it stocks the galleys and dropping glass bottles for cans. g