To limit emissions while he flew across the globe measuring soot, pilot Matevž Lenarčič tweaked both his flight path and his plane. Flying high reduces drag, but thin air has less oxygen for a combustion engine. So Lenarčič replaced his Pipistrel Virus's stock engine with a turbo one to get enough power at high altitudes (he hit 29,413 feet next to Everest). For endurance while crossing oceans, he added fuel tanks to the wings. Lenarčič averaged 36.8 miles per gallon, about double the typical efficiency of small planes.