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  • 2007 GMC Sierra

    General Motors’ newest generation of full-sized pickup trucks is better than ever

    By Nina Russin

    2007 GMC Sierra

    2007 GMC Sierra

    Through all of its ups and downs, one thing that General Motors has consistently excelled at is producing full-sized pickup trucks. One of the reasons is that engineers have incorporated engine technology from the Chevrolet Corvette into the truck chassis. Utilizing the aluminum engine block from the Corvette keeps weight out of the truck, while at the same time offering exceptional power.

    In addition, engineers seem to have a good understanding of exactly what their customers are looking for, and they accommodate their buyers by offering a wide variety of handling, towing and suspension packages. Whether the buyer is a construction worker who needs to haul large payloads, or an enthusiast who desires exceptional off-road capabilities, there’s a full-sized GM pickup designed to meet the need.

    In this new generation of trucks, engineers also focused on improving the ride quality of their trucks, specifically, making the ride and handling features feel more car-like. That involved enhancing torsional rigidity for better steering response, reducing noise intrusion into the cabin, bringing passenger safety features up to speed, and making the truck interiors more luxurious.

    I had a chance to drive the new GMC Sierra pickups at a media event in the Phoenix area this past November. Our drive route included a long section of dirt road northwest of town, as well as some winding two-lane roads that lead from Wickenburg to Prescott. A 3,000 foot elevation change allowed me to test the low-end torque of the new engines, while frequent switchbacks leading up to Prescott were a good test of the new rack-and-pinion steering system.

    A horse is a horse is a horse, of course…

    Back when I was a kid, I was a big fan of “Mr. Ed,” a television show that featured a talking, slightly irreverent horse. One thing I learned from Mr. Ed is that there’s no substitute for good old-fashioned horse sense, especially in a truck engineer.

    At the end of the day, a full-sized pickup isn’t just a pretty face. It’s a workhorse, whose primary purpose is to haul and tow big loads over crappy roads and not break down. That’s why the GMC truck engines utilize pushrods rather than overhead cams.

    High revving engines are great for racecars that run on oval tracks with teams of mechanics in the pits. The idea isn’t so hot for a pickup truck that might break down in the middle of nowhere. The pushrod engines in the GMC Sierras don’t spin very fast, but they have enough displacement to produce mammoth amounts of horsepower and low-end torque: up to 403 horsepower and 417 lbs.-ft. of torque on the 6.2-liter engine.

    The aluminum block reduces vehicle weight and enhances fuel economy. Variable valve timing automatically adjusts the time when the valves open and close according to engine load, allowing for more overlap when power demands are high, but minimizing it for reduced emissions during normal cruising conditions.

    Driving the pickup up the Yarnell grade towards Prescott, I had to remind myself that I was driving a large truck and not a passenger car. When I goosed the accelerator, the truck responded with a surge of power, and the kind of sure-footed acceleration that can only happen with a flat, even torque curve.

    The gasoline engines are mated to a longitudinally mounted six-speed automatic: one of the new “smart” transmissions that engineers have been using for about ten years. They are exceptionally durable transmission, and they have the advantage of being able to change shift points using software, rather than making mechanical changes to the governor.

    An optional cat back exhaust system opens up the exhaust to enhance engine power, while keeping the vehicle emissions compliant.

    A new rack-and-pinion steering system has the rack mounts on the engine crossmembers to reduce lash. That, combined with a 234% increase in torsional stiffness over the previous generation truck made the steering much more responsive. Despite the vehicle’s size, it was easy to get a sense of where the wheels were, and to steer the truck through tight turns.

    Dirt Dog

    New for ’07 is a Z71 off-road package, available on two and four-wheel drive models. Like the Z71 enhancements to other GMC models, this one includes suspension enhancements, special tires and skid plates. I drove both the Z85 and Z71 suspensions on the dirt mining roads around Lake Pleasant. The Z85 package is tuned for towing, but lacks the off-road enhancements of the Z71.

    For most uses, either set-up works well. Standard stabilitrak and antilock braking on all models keeps the wheels tracking straight, and prevents the tires from spinning out of control on loose dirt. All models except duallies also come with a standard tire pressure monitoring system.

    The Z71 set-up does protect underbody components on rough trails where there are errant roots and rocks, and allows for more suspension travel. However, both models were easy to drive at reasonable speeds on the 40-mile dirt section, and there was no problem with braking.

    Buyers who want to trick out their trucks can also choose a suspension designed to accept 20-inch wheels as opposed to the standard 16 and 17 inch rims. There is also a NHT maximum trailering package for those who regularly tow large trailers and boats. The new trucks are designed to tow up to 13,000 pounds if properly equipped.

    Plush interior

    The new Sierra has interior options that rival luxury cars. With prices on these trucks reaching the $40,000 mark for highly optioned one ton models, there’s a good chance that they will be a family’s primary mode of transportation when they are not on the job. In keeping with that theme, buyers can opt for a touch-screen navigation system, DVD rear entertainment system, and a variety of MP3 compatible audio systems.

     The newest generation of OnStar that comes standard on all models also has a voice-activated navigation option.

    The new trucks make extensive use of quiet steel in order to reduce noise intrusion into the cabin. There is an insulating blanket over the transmission tunnel to block road noise, and a new acoustic treatment for the back of the cab to block any noise coming in from the cargo bed.

    The passenger cabin is safer than ever before, thanks to increased use of high strength steel in key areas. Engineers stiffened up the floor pan, added additional structure to the front (A) pillars, and enhanced the knee bolsters in front. In addition to front airbags, buyers can opt to add side curtain airbags that protect both rows of passengers.

    The rear doors on crew cab models open wider than before: up to 170 degrees to make it easier to enter and exit the second-row seats. The rear seats also fold up to create a larger cargo space inside the cabin. Extended and crew cab models come with a power sliding rear window.

    There are plenty of bins and cubbies throughout the cabin to store electronic gadgets, cell phones, and bottles.

    Available accessories include tubular assist steps that make it easier to reach inside the bed, and several cargo system for the rear of the truck. There is an available bed extender, side rails designed to hold a rack above the cargo bed, an overhead rack, roof rails and cross bars, and a tonneau cover for the cargo bed.

    Available diesel engine

    In addition to the gasoline engines, buyers can also choose a 6.6-liter turbo-diesel rated at 365 horsepower, with 660 lbs.-ft of torque. The diesel engine is also mated to a six-speed automatic transmission. There is no longer a manual transmission option for the full-sized trucks.

    Pricing begins at $21,000

    Pricing for the newest GMC Sierra pickups begins at $21,210 for the 1500 regular cab, two-wheel drive model. Four-wheel drive adds about $5,000 to the base price. Fully-equipped four-wheel drive one ton models cost about $40,000. The new GMC Sierra full-sized pickup trucks are currently rolling into dealerships nationwide.

    Base price: $21,000 
    Price as tested: N/A
    Horsepower: 315 Hp*
    Torque: 338 lbs.-ft.  
    Antilock brakes: Standard
    Side curtain airbags: Option
    First aid kit: No
    Towing: Yes
    Off-road: Yes
    Bicycle friendly: Yes
    Fuel economy:N/A
    Comments: * Specs are for the 5.3-liter aluminum engine. Fuel economy figures and pricing will be available later.