Where did you get 58mpg?

The only global number was: “In 2018, CO₂ emissions totalled 747 million tonnes for passenger transport, for 8.5 trillion revenue passenger kilometres (RPK), giving an average of 88 gram CO₂ per RPK.[2] A 88 gCO₂/km represents 28 g of fuel per km, or a 3.5 L/100 km (67 mpg‑US) fuel consumption.”

Anyway that’s not measuring direct fuel consumption in flight but estimating fuel used by the industry to transport passengers. Sort of like including fuel transportation costs to gas stations as part of a cars fuel efficiency. It’s also using US numbers to do so which likely overstate fuel consumption.