By Larry E. Hall
The GMC Sierra Hybrid pickup truck’s gasoline V8 engine and electric motors provide a not-insignificant 33-percent increase in overall fuel mileage and roughly 40-percent better mileage in city driving compared to the standard model. Those numbers make it difficult to understand why anyone would think hybrid technology is the exclusive domain of small or mid-size cars.
Today, pickup sales are overwhelmingly slanted toward buyers who truly need them; those in the building trades, service industries and agriculture. Therefore, any hybrid truck purchased is taking the place of a conventional gas powered pickup and the buyer is driving a more efficient vehicle that, by the way, also produces less carbon dioxide. How can that not be a good thing?
To meet the needs of buyers, the GMC Sierra Hybrid trumpets the critical stats for full-size pickups. It can tow up to 6,100 pounds and still deliver 20 mpg city/23 highway and 23 combined.
For 2012, GMC continues to offer the Sierra Hybrid pickup in just one body style, a four-door crew cab with a short box. There are two trim levels, 3HA and 3HB, and a choice of either two- or four-wheel drive. Changes for the 2012 model year include a chrome three-bar grille and an available hard-drive navigation radio with AM/FM/SiriusXM stereo with CD/DVD player, MP3 compatibility and USB port. Also, rear vision camera is now standard on the 3HB trim level.
Hybrid Powertrain
It’s no surprise that the Sierra shares the same hybrid system found in the Chevrolet Silverado, since both are built on the same platform and feature the same drivetrain. The hybrid hardware combines a tweaked 6.0-liter, 332-horsepower V8 gasoline engine, a 300-volt nickel-metal hydride battery pack and a two-mode hybrid transmission, referred to at GM as an electrically variable transmission (EVT).
Most of the fuel economy gains come from the EVT. The transmission is made up of two 60-kilowatt electric motors, three planetary gearsets and four fixed gears that use the same space as GM’s six-speed automatic transmission. Essentially the EVT has two drive modes – hence the name “two-mode hybrid.” In the first mode, during stop-and-go and city drives, the Sierra can operate with electric power only, gas engine power only or a combination of both. Like Ford and Toyota hybrids, the Sierra Hybrid shuts the engine off when the vehicle stops, and when it’s time to go, the electric motors propel the big SUV to around 30 mph for a couple of miles.
In the second mode, the V8 engine is the primary source of motivation, and one or both electric motors can run concurrently along with the engine in order to provide a power boost. If the Sierra is pulling a load, the transmission locks out the electrically variable gears and both electric motors. It shifts over to the four fixed gears, so the V8 is the sole source of power. A computer monitors the entire system and determines every 1/100th of a second what method is the most efficient means to propel the vehicle.
The crux of the Sierra Hybrid’s powertrain is the V8 engine with cylinder deactivation technology, which shuts down four of the eight cylinders when additional power is not needed. Camshaft phasing, and late-intake valve closure allows even more efficient engine operation.
Exterior and Interior
Small hybrid badges on the front fenders and tailgate and a standard tonneau cover are the only visual differences between the Hybrid and a gasoline Sierra. Redesigned for the 2007 model year, it’s a conservative design that relies on the power of the rectangle, emphasized by the big, squared-off chrome grille with big, red squared-off GMC letters. First impressions are it’s beefy, yet handsome.
The interior is sized like American sedans of yore – it’s Texas and Alaska in a world crammed full of Rhode Island and Delaware cars. Seats are large, supportive and conducive to long periods in the saddle. In the base 3HA there’s a cloth covered 40-20-40 split bench seat up front that is power height adjustable for the driver. Combined with the rear bench, this configuration can seat up to six. Grab the premium 3HB and you’ll find comfortable leather bucket seats for the driver and the front companion. Regardless of model choices, this is a crew cab and there’s enough head, should and leg room that even with six people there’s a feeling of spaciousness.
The 2007 makeover resulted in a cabin that discarded cheap, flimsy plastics and replaced them with quality-looking and feeling materials and nearly invisible seams. The dashboard is simple with large controls – from the door handles to the radio and climate control knobs, most can be operated wearing work gloves. It’s a basic design, but logical and pleasant.
On The Road
The Sierra Hybrid drives less like a truck and more like a full-size SUV. Ride quality is quite good; only certain bumps and surfaces betray the solid rear axle. To smooth out the ride, engineers developed a mid-body hydraulic mount for the Hybrid. The improvement was so apparent that GM added the mount on all of its pickup trucks.
As with all big pickups, push the Sierra hard on a curve and body roll is noticeable. The electrically boosted steering is on the numb side, but there is no need to constantly adjust the steering wheel to keep it between the white lines. Brakes are impressive for a hybrid vehicle this big. There are three brake systems that are electronically calibrated to bring the Sierra to a stop: standard four-wheel disc brakes, the electric motors in the transmission, and hydraulic regenerative brakes that use the electric motors to capture and store brake energy in the truck’s batteries.
GM’s press introduction of their two-mode hybrid pickups included both the GMC Sierra Hybrid and Chevy’s Silverado Hybrid. I spent equal time in both trucks and since then have driven the 2WD and 4WD Silverado Hybrids for hundreds of miles and both trucks returned fuel economy numbers at, or slightly above, the EPA estimates. I would expect similar performance from the Sierra Hybrid.
I found that accelerating from a stop rather briskly, and then easing off the accelerator to allow the electric motors to take over, gave us the most distance in electric-only drive up to around 30 mph. Same procedure works for implementing the V4 operation of the engine – at around 40 mph, smoothly boost speed and then ease off. Of course when power acceleration is really needed, a quick, firm push on the accelerator unleashes the V8’s 332 horsepower and 367 pound-feet of torque, plus assist from the electric motors.
Economics
If you are dead set on buying a hybrid pickup there are only two choices, the GMC Sierra Hybrid and its near twin Chevrolet Silverado Hybrid. Even though the Sierra is the more upscale of the two with more standard content, it is only around $400 more than the Silverado. The somewhat Spartan 3HA 2WD has a sticker price of $39,635; the 4WD is priced at $42,785. For a luxurious interior environment, the 3HB 2-WD starts at $46,415 and jumps to $49,565 with 4WD. Both trim levels have a high content of standard features, and the hybrid powertrain adds roughly $3,500 to a comparable non-hybrid pickup, which returns just 15 mpg city/21 mpg highway and a combined 17 mpg.
Since a crew cab is the Sierra Hybrid’s only body style, appeal is somewhat limited. And, those needing either a longer bed or more than the 6,100 pound towing capacity, a regular Sierra or another brand may be the best option. If fuel economy and more towing/hauling capabilities are needed, Ford’s F-150 with the V6 EcoBoost engine is rated at 16 city/22 highway/18 combined and can tow 11,300 pounds.
A contractor who drives high-speed rural highways from job-to-job will find it difficult to justify the hybrid’s loftier price. But the Sierra Hybrid should help reduce fuel costs for any in-city or suburban company. And that’s a good thing.
Prices are Manufacturer Suggested Retail Price (MSRP) at time of publication and do not include destination charges, taxes or licensing.
0 comments:
Post a Comment