Two-mode hybrid propulsion system is a patented hybrid technology that optimizes fuel economy for various driving conditions. A sophisticated control module in the two-mode hybrid system helps determine the amount of power or torque that’s required at a given moment and seamlessly selects the appropriate operating mode. The modes are:
First Mode: Used at low speed and with light loads. Vehicle can operate in three ways: electric power only, engine power only, or a combination of electric and engine power.
Second Mode: Used primarily at highway speeds and includes Active Fuel Management. Provides full engine power when conditions demand it, such as passing, trailer towing and climbing steep grades.

Every two-mode GMC hybrid has these in common:

Sierra Hybrid (20 mpg city) is the first two-mode hybrid in a full-size pickup truck which results in a 33% increase in EPA estimated city fuel economy compared to our most efficient gasoline-only Sierra (15 mpg city). There is no sacrifice on capability; the Sierra Hybrid can handle over 1500 lbs of payload.13

The GMC Sierra Hybrid is up to 54% more fuel efficient in the city than the Ram 1500 and Toyota Tundra.14
At low speeds and light loads, Sierra Hybrid reduces fuel consumption by shutting off the engine and operating on electric power alone. It can also run on engine power alone, or a combination of both gas and electric. In the city, this technology offers an EPA-estimated 20 MPG.
At highway speeds Sierra uses Active Fuel Management in either V4 or V8 operation—sometimes with an extra boost of electric power—as conditions warrant. Full V8 is available for trailer towing, passing or pulling on a long, steep grade. On the highway, Sierra Hybrid has an EPA-estimated 23 MPG.

Full-size SUVs are all about space. They are not particularly known for their fuel efficiency, which makes Yukon Hybrid and Yukon Denali Hybrid such a pleasant surprise. Both are equipped with features to help optimize fuel efficiency, while still providing you with the cargo space you need.
NiMH battery technology can store a lot of energy in a small space. In fact, the 300-volt battery pack is strong enough to propel your Yukon from 0 to over 25 mph on electric power alone, yet small enough to fit under the second-row seat between the steel frame rails. This leaves your cargo space and passenger capacity unchanged from other Yukons.
To conserve fuel at low speeds or under light loads, this transmission has two integral electronic motors that engage to give you smooth, effortless power. At highway speeds or heavier loads with its 6.0L V8 VVT engine engaged, it acts as a normal automatic transmission.
• GMC Yukon Hybrid and the GMC Yukon Denali Hybrid are the most advanced full-size SUVs available today.15
• The GMC Yukon Hybrid has best in class fuel economy.16
• The Yukon Hybrid has up to 66% better city fuel economy than any other full-size SUV in its class.17
• The Yukon Hybrid is the full-size SUV that offers better city fuel economy and more power than a 4 or 6-cylinder Toyota Sienna.18
• The Yukon Hybrid has an estimated 33% improvement in city fuel economy as compared to the non-hybrid engine.19
• The Yukon Denali Hybrid has best in class fuel economy.20
1. E85 is 85% ethanol and 15% gasoline. Find E85 stations near you.
2. EPA estimated MPG 15 city/21 hwy. with the 5.3L V8 engine. Based on 2011 GM Large Pickup Segment.
3. EPA est. MPG (2WD/4WD) 20 city/ 23 hwy.
4. EPA est. MPG (2WD/4WD) 20 city/ 23 hwy. Based on 2011 GM Large Pickup segment.
5. EPA estimated MPG 15 city/21 hwy. Based on 2011 GM Large SUV Segment.
6. EPA est. MPG 20 city/23 hwy. Based on 2011 GM Large Utility Segment.
7. Based on new EPA estimates.
8. EPA estimated MPG (2WD) 32 hwy. Based on 2011 GM Compact SUV-Crossover segment.
9. Up to 600 miles. Based on 2011 GM Compact SUV-Crossover segment.
10. Sierra 1500 with 5.3L V8 engine EPA est. MPG (2WD) 15 city/21 highway; (4WD) 13 city/18 hwy. Sierra 1500 with 6.2L V8 engine EPA est. MPG (2WD) 13 city/18 highway; (AWD) 12 city/18 highway. Sierra Hybrid with 6.2L V8 engine EPA est. MPG (2WD) 20 city/23 highway; (4WD) 20 city/23 hwy. Yukon and Yukon XL models with 5.3L V8 engine EPA est. MPG (2WD) 15 city/21 highway; (4WD) 15 city/21 highway. Yukon Hybrid & Yukon Denali Hybrid models with 6.0L V8 engine EPA est. MPG (2WD) 20 city/23 highway; (4WD) 20 city/23 highway. Yukon Denali and Yukon Denali Hybrid models with 6.2L V8 engine EPA est. MPG 14 city/18 highway; (AWD) 13 city/18 highway.
11. Based on the 2011 GM Large Pickup segment. EPA est. hwy.: Sierra XFE 22 MPG/Sierra Hybrid 23 MPG, Tundra 20 MPG, F-150 21 MPG, Ram 20 MPG.
12. Yukon Hybrid 2WD with EPA estimated MPG 20 city/23 highway. Sierra Hybrid 2WD with EPA estimated MPG 20 city/23 highway.
13. Maximum payload capacity includes weight of driver, passengers, optional equipment and cargo and 6,100 lbs of trailering capacity. (Maximum trailer weight ratings are calculated assuming a base vehicle, except for any options necessary to achieve the rating, passengers and cargo will reduce the maximum trailer weight your vehicle can tow. See your GMC dealer for details).
14. EPA est. MPG 20 city Sierra Hybrid; 13 city Ram 4WD; 13 city Tundra 4WD and up to 66% more fuel efficient in the city than the Ford F-150.
15. EPA est. MPG (2WD/4WD) 20 city/ 23 hwy.
16. EPA est. MPG 20 city/23 hwy. Based on 2011 GM Large Utility Segment.
17. EPA est. MPG 20 city. Based on 2011 GM Large Utility Segment.
18. EPA est. MPG Yukon 20 city, Toyota Sienna 19 City (4 cyl) & 18 City (6 cyl)
19. EPA est. MPG 20 15 city vs city.
20. EPA est. MPG 20 city/23 hwy 2WD. Based on 2011 GM Large Utility Segment.