GM releases two-mode hybrid

Nov. 1, 2008
General Motors has begun production of the 2009 Chevrolet Silverado/Sierra two-mode hybrid, a full-size pickup that achieves 40% greater city fuel economy

General Motors has begun production of the 2009 Chevrolet Silverado/Sierra two-mode hybrid, a full-size pickup that achieves 40% greater city fuel economy and a 25% improvement in overall fuel economy.

Partnering the two-mode system and a 6.0-liter gas V-8, the Silverado hybrid provides all-electric driving at low speeds, allowing fuel savings to be realized even when the truck is fully loaded or towing a trailer. The Silverado hybrid can tow up to 6100 pounds.

Going on sale in the first half of 2009, it is based on the Silverado platform that was introduced for the 2007 model year. It will be offered in the crew cab body style; 2WD and 4WD models. Each model comes standard with StabiliTrak electronic stability control system, a locking rear axle, and a trailering package.

Besides increased fuel economy, the electrically variable transmission also provides trailering capability, enhancing the smoothness and driving quality when towing. Electric drive is enabled up to approximately 30 mph, even when towing, allowing fuel savings when the truck is towing a trailer.

The 2009 Silverado hybrid is the second full-size hybrid pickup from Chevrolet. The previous Silverado was offered as a mild hybrid that professionals found useful as a power generator at worksites.

EPA-estimated fuel economy for 2WD models is 21 mpg in the city and 22 on the highway; 4WD models are estimated at 20 mpg in both city and highway driving. That mileage, combined with the Silverado hybrid's 26-gallon fuel tank, delivers a cruising range of more than 500 miles with 2WD models and more than 470 miles with 4WD models.

The Silverado 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 Silverado to launch and drive up to 30 mph on electricity alone, but it also allows the Vortec 6.0L V-8 engine to operate in its more economical V-4 mode for longer periods.

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.

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.

The two-mode system was first introduced on the 2008 Tahoe hybrid.

Integration of the hybrid system on the Silverado is seamless — the battery pack is located beneath the rear seat — and delivers a quiet driving experience. Contributors to this include:

  • A 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.

  • Low-rolling resistance, “quiet-tuned” P265/65R18 tires for reduced road noise.

  • The 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.

  • The 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.

It has specifically tuned shocks and a new hydraulic body mount. Located on the passenger side of the chassis, the hydraulic mount provides an improvement in highway driving smoothness, particularly on rough or choppy road surfaces.

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

Production began in the fall on the new XFE (Xtra Fuel Economy) models of the 2009 Chevy Silverado and GMC Sierra. The vehicles use a combination of mechanical, aerodynamic, and mass-reducing enhancements to deliver a 5% increase in EPA-estimated highway fuel economy and more than 7% improved mileage in city driving.

GM says the enhancements make Silverado XFE and Sierra XFE models the most aerodynamic full-size pickups in the industry, with a 0.412 coefficient of drag (cd).

The new XFE models are available on 2WD vehicles equipped with the 5.3L V-8 and six-speed transmission. They achieve 15 city and 21 highway mileage ratings versus comparable non-XFE models' 14/20 ratings.

The increased efficiency does not come at the expense of capability. Towing ratings for the Silverado and Sierra increase from 6600 pounds to 7000 pounds due to the new, six-speed transmission and high-capacity cooling package.

Most regular-production options for all models are available. Silverado XFE and Sierra XFE are offered in 2WD crew cab body styles only.

They are powered by a 5.3L FlexFuel V-8 (LC9) engine that's built with a mass-reducing aluminum cylinder block and heads. It is rated at 315 hp and 338 lb-ft. The engine is backed by a Hydra-Matic 6L80 six-speed automatic transmission.

A rear axle equipped with a fuel-saving 3.08 ratio is also standard on all XFE models. Lightweight aluminum wheels and low rolling resistance tires (with higher tire pressure) also are included on all models.

Dan Tigges, commercial product manager for full-size trucks, said GM has gained .9 of a point of full-size market share in 2008 as the market has fallen off by 370,000 units.

“When we launched the new truck in 2007, the market was down 67,000, but even with that and the fact that Toyota was in the market for the first time, GM did manage to gain market share,” he said. “In heavy duty, GM gained over 2.8 points of market share.”

Mid-size lineup

The Colorado/Canyon pickups enter 2009 with a host of performance enhancements, including a new 5.3L V-8 engine option and new brake system.

The new 5.3L V-8 is available on extended cab and crew cab models. It pumps out 300 hp, nearly 25% more than the available 3.7L I-5 engine. It also delivers 320 lb-ft of torque for a maximum towing capacity of 6000 pounds.

A revised fuel control module helps most 2009 Colorado/Canyon models equipped with the 2.9L and 3.7L engines achieve better fuel economy than previous models. The greatest mileage improvement comes in 4WD models equipped with the 2.9L engine and manual transmission, where the estimated highway rating increases to 25 mpg — an increase of nearly 14% over the '08 rating.

All models receive a new brake system that delivers greater stopping power and an improved brake pedal feel. The system features four-channel ABS with yaw control for flatter, more controlled stopping during panic stops, and improved control on slippery surfaces.

The sport-tuned ZQ8 suspension returns later in the '09 model year on extended and crew cab models. It features revised tuning, all-new 18-inch Xtreme, split six-spoke aluminum wheels and performance tires and a new 5.3L V-8 engine as standard equipment.

Steering and track-tuned suspension enhancements stiffen the suspension by about 30%. The steering system receives a high-performance cooler.

Additionally, the ride height is “slammed” — it is lower than the standard Z85 suspension by approximately 1" — and ZQ8-equipped trucks ride on 18"×8" aluminum wheels and low-profile sport tires.

Head curtain side air bags act like a protective curtain when deployed, unfolding from the roof rail between the A-pillar and side window header. When the bag deploys in a moderate to severe side impact, it is angled somewhat toward the window to help provide protection for front- and rear-seat outboard passengers.

Other safety features include: energy-absorbing steel structure; standard four-wheel ABS brakes; rack-and-pinion steering; a driver information center; three-point lap and shoulder belts in all three rear seating positions on crew cab models and LATCH (Lower Anchors and Tethers for Children) system anchors for child safety seats. This system provides two lower anchors and a top tether anchor used to secure a child seat to the vehicle seat structure. These anchorages are designed to make it easier to properly install compatible child safety seats.

Express/Savana 4500 commercial cutaway van

Flexibility and durability are featured on the 4500 chassis, which was engineered to support the needs of three primary applications: school buses, shuttle buses, and ambulances.

The Express/Savana 4500's capability is supported by a new, stronger chassis that enables a 14,200-lb GVW with lower mass — giving it a payload rating of 9100 lb.

It is offered with a gas V-8 and GM's 6.6L Duramax turbo-diesel V-8, offering better fuel economy over larger engines. With the new, strong frame and robust powertrains, the Express/Savana 4500 offers up to a 20,000-lb GCWR for strong towing and RV capability.

Frame enhancements, chassis design details, and drivetrain features deliver flexibility in a single platform, while the 4500's more robust body structure is designed to handle the extreme duty cycle encountered by many cutaway vehicles.

Highlights include: reinforced frame assembly; new rear axle with reinforced housing, gears, and axle tubes; upgraded rear spring hanger bolt attachments and leaf spring shackle assembly; high-capacity rear spring assembly; upgraded front ball joint material; revised front and rear shock tuning; rear stabilizer bar; enhanced parking brake system with thicker rear brake rotors for improved heat dissipation; enhanced driveshaft hanger; higher-capacity radiator; and standard transmission cooler.

Brackets added to the upper and lower portions of the frame's side rail bulkheads provide reinforcing strength, as do kick-up reinforcements near the rear axle area. The body-in-white structure is also strengthened, with 10% thicker steel used in key areas, as well as additional spot welds and structural adhesive.

With approximately 2500 lb in GVCW gained with the 4500 chassis, it makes an ideal platform for RVs and offers increased seating for school bus applications.

The 4500 chassis is available with a Vortec 6.0L gasoline V-8 or the Duramax 6.6L V-8 turbo-diesel. The emissions-compliant Duramax 6.6L was introduced as an interim change during the 2007 model year, and features a host of enhancements that enable it to deliver reduced emissions using cleaner, federally mandated Ultra Low Sulfur fuel. It is rated at 250 hp and 460 lb-ft of torque.

A new, electronic variable cooling fan is used with the Duramax engine. It delivers improved cooling control and quieter operation than a conventional mechanical (engine-driven) fan.

The Vortec 6.0L gas engine features variable valve timing for enhanced performance and optimized fuel economy; it is rated at 323 hp. The Vortec 6.0L is based on GM's Gen IV small-block V-8 engine family that features strength-enhancing features such as a deep-skirt cylinder block and cross-bolted six-bolt main bearing caps.

A Hydra-Matic HD 4L85E electronically controlled four-speed automatic transmission backs both available engines. It was designed for the heavy-duty use of commercial cutaway vans and features a brazed torque converter turbine, induction-hardened turbine shaft, five-pinion reaction and output gear carriers and an improved overrun roller clutch.

All 4500 chassis (except school bus applications) with the 14,200-lb GVWR and Duramax diesel engine receive a new, 57-gallon rear-mounted fuel tank that was designed with input from upfitters. The tank is mounted lower on the chassis, providing a flat mounting position for ambulance bodies and more.

About the Author

Rick Weber | Associate Editor

Rick Weber has been an associate editor for Trailer/Body Builders since February 2000. A national award-winning sportswriter, he covered the Miami Dolphins for the Fort Myers News-Press following service with publications in California and Australia. He is a graduate of Penn State University.