With the base powertrain, both the 2012 GMC Yukon and its long-wheelbase version, the Yukon XL, earn respectable fuel economy numbers for the class. The EPA rates Yukons with the 5.3-liter V-8 at 15/21 mpg--still low in absolute terms, but better than other big utes like the Armada or GL-Class.
Upgrading to the 6.2-liter V-8 on XL versions and in the Denali drops gas mileage to 14/18 mpg, or 13/18 mpg with all-wheel drive.
The Yukon lineup does include a Hybrid edition, a vehicle that really only is approached in efficiency by the turbodiesel version of the Benz GL-Class. The Yukon Hybrid ekes out 50 percent better city fuel economy, for an overall EPA rating of 20/23 mpg, while it still can tow 5,000 pounds.All standard Yukon models are also E85 (85-percent ethanol) compatible; but when you fuel up with ethanol you'll get an EPA-estimated 11 mpg city, 16 highway.