Thanks to the addition of an all-new 8-speed automatic transmission, the updated 2015 GMC Yukon Denali and Yukon XL Denali models now lead several competitors in horsepower, torque and highway fuel economy ratings.
Both the Yukon Denali and Yukon XL Denali now pair their 6.2-liter EcoTec3 V-8 engines with a new Hydra-Matic 8L90 eight-speed automatic transmission, designed to be more fuel-efficient than the Denali’s previous six-speed automatic. EPA highway mileage estimates for two-wheel drive Yukon Denali and Yukon XL Denali models increase to 10.7 L/100 km with the eight-speed automatic, while the EPA city mileage estimate for the four-wheel drive Yukon Denali model rises to 15.7 L/100 km.
Within its segment, the Yukon Denali continues to deliver unrivaled power and efficiency. Denali’s 6.2L EcoTec3 V8 delivers a segment-leading 420 hp and segment-leading 624 Nm of torque with highway fuel economy.
Compared to the Yukon Denali’s previous six-speed transmission, the new 8L90 transmission offers smaller steps between gears, allowing the engine to efficiently leverage its peak power bands. The wider gearing spread also allows the use of a lower 3.23:1 rear axle ratio, which reduces engine speeds and fuel consumption, especially during highway cruising.
Comfort and capability are not compromised for fuel economy. Not only is the 8L90 transmission capable of handling more torque than the six-speed transmission it replaces, but its shift controls and solenoids are more responsive and provide quicker shift times. A new torque converter also delivers smoother performance at low speeds, especially when carrying heavy loads or pulling trailers. Tow ratings – up to 3810 kg (8,400 pounds) for the Yukon Denali and 3674 kg (8,100 pounds) for the Yukon XL Denali – are unaffected by the addition of the eight-speed transmission.