In transmission-land, more speeds are usually better (so long as you keep total gear count to a reasonable level, lest you end up with an abominable CVT). So it is good news that, as part of a mid-model-year update to its new 2015 Yukon Denali line, GMC is now pairing a new eight-speed automatic transmission with its stonkin’ 6.2-liter V-8, which pumps out a massive 420 horsepower and 460 lb-ft of torque.
Thus equipped, the Yukon Denali not only gets a transmission that’s better able to access the meatiest parts of its powerband, as we discovered when we drove it earlier this year, but its new gearbox can utilize a lower 3.23:1 rear-axle ratio that helps bring fuel economy up a tick for most models. Rear-wheel-drive Denali and Denali XL examples can now achieve 1 additional mpg on the highway—going from 15/21 mpg to 15/22—while short-wheelbase 4WD models do 1-mpg better in the city, going from 14/21 to 15/21. At 14/20 mpg, four-wheel-drive Denali XLs see no improvement at all.
While it still can’t touch the Prius in the next lane, the big ute’s fuel-economy numbers are now more competitive than ever within its peer group, right on top of, and in some cases beating, certain 2015 Lincoln Navigator models with their less powerful twin-turbocharged V-6.
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Incidentally, the eight-speed auto now comes standard on all GM trucks with the 6.2, which include certain 2015 Chevrolet Silverado and GMC Sierra models and all Cadillac Escalades. The Denalis also get 4G LTE Wi-Fi and wireless-device charging as part of the midyear 2015 update. The eight-speed pickups have already started arriving in dealerships nationwide, says GM, and the Denalis with the transmission, which have been in production since last month, will follow shortly.
