Chicago 2008: GMC Sierra Two-Mode Hybrid is coming

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As projected a few days ago, GMC has announced a hybrid version of the Sierra full-size pickup truck. This one should come as a surprise to no one. Aside from badging and the grille and headlights, this is the same as the Silverado hybrid that was announced at the LA Auto Show. It has the same two-mode hybrid system that is appearing in other GM full-size trucks. The 300V nickel metal hydride battery resides under the second row seat. The truck gets some aerodynamic tweaks including a deeper front air dam and a standard tonneau cover over the bed. Towing capacity from the 6.0L V-8 and hybrid powertrain is 6,100 lbs for the two wheel drive and 5,900 lbs for the four wheel drive. Fuel efficiency should increase by forty percent around town and twenty-five percent overall.
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[Source: General Motors]


CHICAGO – GMC announced the 2009 GMC Sierra Hybrid, a powerful full-size pickup that achieves 40-percent greater city fuel economy and a 25-percent improvement in overall fuel economy while delivering the capability expected of a full-size truck – including a 6,100-pound (2,767 kg) towing capacity.

Partnering General Motors' patented two-mode hybrid system and a powerful 6.0L gas V-8, the Sierra Hybrid delivers highly efficient performance, including all-electric driving up to 30 mph (48 km/h). That allows fuel savings to be realized even when the truck is fully loaded or towing a trailer.

"The Sierra Hybrid represents GMC's commitment to engineering excellence, delivering a fully functional truck that offers a significant improvement in fuel economy," said Jim Bunnell, GMC general manager. "Sierra Hybrid will deliver fuel economy that is expected to be the best in the full-size pickup segment, exceeding the current mileage leader – the non-hybrid Sierra."

The Sierra Hybrid goes on sale in the fourth quarter of 2008 and is based on the strong and capable Sierra platform that was introduced for the 2007 model year. It will be offered in the Crew Cab body style on both 2WD and 4WD models. Each model is equipped with several standard, popular features, including StabiliTrak electronic stability control system, a locking rear axle and a trailering package. Sierra Hybrid also offers dual-stage frontal air bags and head curtain side air bags, and it is the only full-size truck with five-star side-impact ratings in federal crash tests.

Hybrid details

The Sierra Hybrid's fuel-saving performance is derived from GM's advanced Electrically Variable Transmission (EVT) and 300-volt nickel-metal hydride Energy Storage System (ESS), which work in concert with the standard 6.0L V-8 gasoline engine with Active Fuel Management (AFM) and late intake valve closing (LIVC) technology. GM's hybrid technology system not only enables the Sierra to launch and drive up to 30 mph on electricity alone, it also allows the Vortec 6.0L V-8 engine to operate in its more economical V-4 mode for longer periods.

As part of the vehicle's emission control system, the ESS is warranted for eight years/100,000 miles.

With GM's two-mode hybrid system, the electric power used to propel the vehicle is generated by the hybrid system itself. When the brakes are applied or the vehicle is coasting, the electric motors within the hybrid system create electricity that is stored in the 300-volt battery. This stored energy is used to move the vehicle and the regenerative braking cycle is renewed.

The two-mode hybrid system provides seamless, dependable power on demand in an efficient package. In fact, its electric motor is less than half the size of those in single-mode hybrid systems. This technology was developed and is still used in fleets of hybrid transit buses in more than 70 North American and European cities. Scaled-down for use in passenger vehicles, the two-mode system delivers fuel savings where it is needed most – in large vehicles with high levels of capability. The two-mode system was first introduced on the 2008 Yukon Hybrid. It is a core part of GM's energy diversity efforts, which are centered on reducing dependence on petroleum, improving fuel economy, reducing emissions and minimizing the automobile's impact on the environment.

With the fuel savings of the hybrid system and Sierra's 26-gallon (98-liter) fuel tank, the Sierra Hybrid has a cruising range of more than 500 miles (800 km).

Quiet and smooth

Integration of the hybrid system on the Sierra is seamless – the battery pack is located beneath the rear seat – and perceptible only in what it lacks: noise.

"The Sierra Hybrid is exceptionally quiet," said Mark Cieslak, vehicle chief engineer. "From a passenger's perspective, the refinement of the hybrid system is quite evident throughout the driving experience, and showcases itself when the vehicle is moving under electric power."

Contributors to the quiet driving experience include:

  • New exhaust system and resonator tuned for the 6.0L engine's Active Fuel Management operation
  • Additional engine intake induction tuning for reduced interior noise and pleasing sound quality
  • Low-rolling resistance, "quiet-tuned" P265/65R18 tires for reduced road noise
  • Electrically driven 300-volt air conditioning compressor reduces vibration and allows the standard, tri-zone HVAC system to cool the passenger compartment even when the gasoline engine is shut off
  • Electrically driven 42-volt variable-assist power steering reduces vibration and provides up to a 0.5-mpg fuel economy improvement by reducing parasitic losses common in belt-driven hydraulic systems
  • Energy Storage System (ESS) cooling system internal fan is tuned to be quiet at low vehicle speeds when the fan could more easily be heard by the occupants

Along with quietness, the Sierra Hybrid also delivers exceptional driving smoothness, thanks to specifically tuned shocks for its Z85 suspension and a new hydraulic body mount. Located on the passenger side of the chassis, the hydraulic mount provides a dramatic improvement in highway driving smoothness, particularly on rough or choppy road surfaces.

"The hydraulic mount makes a dramatic improvement in ride quality," said Cieslak.

Additional details specific to the Sierra Hybrid include aerodynamic aids. A slightly deeper front air dam and a tonneau cover for the bed reduce air drag, fostering maximum efficiency.

Trailering performance

In addition to increased fuel economy, the Sierra Hybrid's electrically variable transmission also provides tremendous trailering capability, enhancing driving smoothness and quality when towing. Electric drive is enabled up to approximately 30 mph (48 km/h), even when towing, allowing fuel savings when the truck is towing a trailer.

"Along with being very smooth, the EVT always provides abundant torque at all rpm levels for easy towing," said Cieslak. "It is particularly helpful on grades, as the EVT's greater ratio spread allows the engine to hold optimal rpm for smooth, steady performance, with no hunting between higher and lower gears."

The EVT incorporates grade braking and tap up/tap down shift control. It also benefits towing on curves or lower-speed back roads, as exceptionally smooth gear transitions eliminate the "shift shock" torque disruption that can occur during abrupt shifts, such as when slowing or braking.

In addition to the eight-year/100,000-mile warranty on the Sierra Hybrid's Energy Storage System, GM's Five-Year/100,000 Mile Powertrain Limited Warranty continues to make GM a better choice for customers. GM's coverage focuses on the complete ownership experience and includes other provisions that competitors do not offer, including transferability to the next owner, more complete coverage of parts, and coverage for new and certified used vehicles. In addition, GM offers complementary programs such as courtesy transportation and roadside assistance.




GMC Sierra Hybrid

Body style / driveline:

full-size, 4-door pickup; front-engine, 2WD & 4WD


body-on-frame, all-welded, fully-boxed, ladder-type channel design, with hydroformed front and rear sections

EPA vehicle class:

full-size pickup

Manufacturing location:

Oshawa, Ontario, Canada



Vortec 6.0L V-8 (LFA)


Sierra Hybrid

Displacement (cu in / cc):

364 / 5967

Bore & stroke (in / mm):

4.00 x 3.62 / 101.6 x 92

Block material:

cast aluminum

Cylinder head material:

cast aluminum


overhead valve, 2 valves per cylinder, variable valve timing

Ignition system:

coil-near-plug ignition, iridium electrode tip/ iridium core spark plugs, low resistance spark plug wires

Fuel delivery:

Active Fuel Management™; sequential fuel injection

Compression ratio:


Horsepower (hp / kW @ rpm):

332 / 248 @ 5100*

Torque (lb-ft / Nm @ rpm):

367 / 497 @ 4100*

Recommended fuel:

regular unleaded

Maximum engine speed (rpm):


Emissions controls:

close-coupled catalytic converter, Quick Sync 58X ignition, returnless fuel rail, fast-response O² sensor

EPA estimated fuel economy (city / hwy):




two-mode continuous electric ratio hybrid transmission with four fixed gears

Gear ratios (:1):










Infinite – 1.70


Infinite – 1.70


1.70 – .5

Final drive ratio:


Vehicle Power System

Power electronics system:

300-volt (transmission, air conditioning); 42-volt (power steering); 12-volt (vehicle accessories)


300-volt (hybrid system); 12-volt (vehicle accessories)



independent, coil-over-shock


2-stage leaf spring

Steering type:

42-volt electric power-assisted rack-and-pinion

Steering ratio:


Steering wheel turns, lock-to-lock:




power-assisted four-wheel discs with fully blended regenerative braking control, standard stability control, traction control and four-channel ABS; vented front discs, solid rear discs; twin-piston front calipers, single-piston rear calipers

Rotor diameter x thickness (in / mm):

front: 13 x 1.18 / 330.2 x 30
rear: 13.5 x 0.79 / 345 x 20


Wheel size and type:

18 x 8-in. six-spoke polished aluminum


P265/65R18 AL2


Wheelbase (in / mm):

143.5 / 3645

Overall length (in / mm):

230.2 / 5844

Overall width (in / mm):

80 / 2032

Overall height (in / mm)


73.8 / 1875


73.7 / 1872

Track (in / mm)


68.1 / 1730


67 / 1702

Min. running ground clearance (in / mm)

9 / 229

Ground to top of load floor (in / mm):

2WD: 32.9 / 835
4WD: 32.7 / 831

Step-in height


32.4 / 824


32.4 / 824

Approach angle (deg)





Breakover angle (deg)





Departure angle (deg)






Crew Cab, Front

Crew Cab, Rear

Headroom (in / mm):

41.2 / 1048

40.5 / 1030

Legroom (in / mm):

41.3 / 1049

38.7 / 983

Shoulder room (in / mm):

65.2 / 1657

65.1 / 1655

Hip room (in / mm):

62.5 / 1588

65.4 / 1663

Curb Weight & Payload

GVWR (lb / kg)

Curb Weight (lb / kg)

Max. Payload (lb / kg)

Weight Distribution (% front / rear)


Crew Cab Short Box

7100 / 3220

5641 / 2559

1459 / 662

59 / 41


Crew Cab Short Box

7300 / 3311

5881 / 2667

1418 / 643

59 / 41

Cargo Box

Cargo volume (cu ft / L):

53.2 / 1506

Length at floor (in / mm):

69.29 / 1760

Width at floor (in / mm):

62.4 / 1586

Width between wheelhousings (in / mm):

50.6 / 1286

Tailgate width (in / mm):

61.5 / 1564

Inside height (in / mm):

21 / 553



5 or 6

Fuel tank (gal / L):

26 / 98

Engine oil (qt / L):

6 / 5.7

Cooling system (qt / L):

14.4 / 13.6

GCWR (lb / kg):

2WD: 12000 / 5443
4WD: 12000 / 5443

Trailer towing maximum with ball hitch (lb / kg):

2WD: 6100 / 2767
4WD: 5900 / 2676

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