The Yukon and Yukon XL are GMC's full-size SUVs. The Yukon XL has a longer-wheelbase than the regular Yukon. Both Yukons are offered in SLE, SLT and Denali models, while the Hybrid comes in a single trim. Each of these models is available in either rear- or 4-wheel drive. Both Yukons offer a standard 320-horsepower, 5.3L V8 engine paired with a 6-speed automatic transmission. The heavy-duty Yukon XL 2500 also offers a 6.0L V8 that makes 352 hp and 382 lb-feet of torque. Yukon Denalis come with a 6.2L flex-fuel capable V8 that capable of 403 hp and 417 lb-feet of torque. The GMC Yukon Hybrid employs GM's 2-mode hybrid system which combines a Vortec 6.0L V8 engine with Active Fuel Management and a sophisticated Electrically Variable Transmission (EVT) system that employs two electric motors that engage to help power the truck for optimal efficiency. The Yukon hybrid can operate at low speeds on electric power alone and the gasoline engine automatically stops and restarts for traffic lights and idle situations. A 300-watt nickel-metal-hydride battery pack is located under the second-row seat of the Yukon Hybrid, maintaining the seat's fold-forward capability. Otherwise, the Hybrid model gets a number of other changes including electric power steering, an electric air conditioning compressor and low-rolling resistance tires. Altogether, the Yukon Hybrid achieves nearly a 30-percent improvement in efficiency over a non-hybrid, with EPA estimates of 20 mpg city and 23 mpg highway. All Yukon models are built on a fully boxed frame, which gives them full truck toughness and helps keep vibrations out of the cabin. A coil-over-shock front suspension and rack-and-pinion steering give the Yukon a surprisingly good ride and reasonably responsive handling. Denali models get a special Autoride suspension system that employs real-time, semi-active adjustable dampers to help reduce body motion. Yet in any of these models, the interior is plush and comfortable and the instrument panel is more like that of Chevrolet's passenger cars and modern crossovers than like Chevrolet and GMC's work-oriented pickup trims. The Yukon comes with a strong set of safety features across the lineup. Each of the Yukon trims includes GM's StabiliTrak stability control, along with anti-lock brakes, seat-mounted front side airbags and head-curtain airbags for the first and second rows, as well as the OnStar suite of services, such as Stolen Vehicle Slowdown and Automatic Crash Response. A side blind-zone alert system is optional. Also no matter the model, tow ratings are strong. The Yukon can tow up to 8,500 pounds, while the Yukon Hybrid can tow up to 6,200 pounds and the Yukon XL can handle trailers up to 8,100 pounds. A heavy-duty 2500 version of the Yukon XL offers a tow rating of up to 9,600 pounds. Most Yukon models include seating for up to eight, with two buckets in front plus second and third-row bench seats good for three across, but a front bench is available on the Yukon XL to fit up to nine. Several upholsteries and styles are offered and both the first and second rows can be heated. Top Denali models include upgraded wheels and chrome trim, a navigation system with XM satellite radio and XM NavTraffic, Bose Centerpoint surround sound system with ten speakers, heated and cooled front seats, perforated leather upholstery and extra power outlets, among many extra features. Among the noteworthy options on the Yukon and Yukon XL are navigation, DVD rear entertainment, remote start, tri-zone climate control, Ultrasonic Rear Park Assist, a rearview camera system and a power-folding second-row seat.