First Drive: 2007 GM HD Pickups

2007 GMC Sierra 2500 HD SLT Extended Cab

First Look



GM’s 2007 Heavy Duty pickups; new bodies, more power, same bones


By Bruce W. Smith / ©2007 Editorial Services

 â€śThese old bones ain’t what they used to be.”

Those words keep flitting around in my head as I glide past slower traffic while powering up a long, steep highway grade in the mountains just East of San Diego. Even though there’s a big 24-foot, Ranger center-console fishing boat latched to the hitch, the 2500 Crew Cab 4×4 I’m driving is hardly taxed by the 5,000 pounds in-tow.

My foot rolls deeper into the throttle and the speedometer needle in the new dash instrumentation climbs at a very satisfying pace—obviously a direct result of having 660-foot-pounds of torque rolling off the crankshaft of the 6.6L Duramax V8 diesel humming from beneath the hood.

Back off the throttle and the Silverado settles down to a smooth, steady, quiet cruise speed of 65mph—uphill.

Gary White, GM North America vice president and vehicle line executive of full-size trucks—and one of my driving partners—says “There’s not a broader, more powerful or more capable lineup of heavy-duty pickups in the industry.”

It’d be tough to find a point on which to challenge his assessment. At least that’s my impression after driving the 2007 GM Heavy Duty pickups—be that a Chevrolet or GMC, two-wheel-drive or four, long bed or short, Regular Cab, Extended Cab, Crew Cab or Dually.

07 HD Silverado towing Ranger 2Those who worry about towing larger boats while keeping within the vehicle manufacturer’s weight-carrying limitations need not worry about such things with the 2007 Heavy Duty GM pickups. The weight-carrying limit is more than 12,000 pounds, so towing a boat like this 24-foot Ranger center-console is a piece of cake—especially with a Duramax diesel under the new bodywork.

“These old bones ain’t what they used to be.” But in reality, the bones really are the same. It’s everything else attached to the frame rails of the last models of GM’s truck/SUV line to get the major make-over that have changed.

The bodies are all-new inside and out; the engines have more power; and there’s a new transmission for the stout 6.0L small-block that serves as the base engine for the line-up.


The General’s all-new Silverado and Sierra 1500 Series (half-ton) pickups, the 2500 (3/4-ton) and 3500 (1-ton) Series Heavy Duty models have taken a big step forward in refinement. They are hard-core work/play trucks that are more civilized and well-mannered than ever before.

In recent issues we’ve touted the new bodies and spacious interiors found in GM’s full-size SUVs and half-ton pickups. Those same attributes are found in the ’07 Heavy Duty models; each model’s cab is just as nicely laid out and comfortable as you’ll find in the other ’07 GM pickups and SUVs.

Although GM engineers left the frame rails alone, they have improved the brakes and steering, improving both to instill a lot of driver confidence regardless of the environment. The trucks just feel “right.”


  •  2500HD (three-quarter-ton) and 3500HD (one-ton) models –
  • 2WD and 4WD drivetrain in all models
  • Three cab styles: regular, extended cab, crew cab and crew cab Dually
  • Three box configurations: standard (6’ 6”); long bed & Dually (8-foot)
  • Choice of 353hp 6.0L Vortec gas or 365hp 6.6L Duramax diesel engines with six-speed automatic transmissions
  • Z85 smooth ride suspension or new Z71 Off Road package (4Ă—4 only)
  • Distinct trim offerings, including two different interiors
  • Segment-best gross combined weight rating of 18,500 pounds (6.0L)
  • Segment-best conventional trailer weight rating of 13,000 pounds (6.6L)  

Where the most eye-catching changes show are in the bodies, which now show big differences between models and brands (Chevrolet/GMC)—most notably the front sheetmetal that conveys a much greater sense of power than their ½-ton counterparts.

The new grilles are more open than found on the 1500 Series, the hoods taller and vented, the headlights slightly larger, and the front fenders wider and more rounded–all working in concert to convey a broad-shouldered, muscular look. 

By the way, the new Dually has a one-piece stamped fender, which really helps smooth its distinctive lines.


It’s under those sculpted hoods of both the GMC Sierra and Chevy Silverado HDs that really separate the men from the boys in the working pickup world.

The base engine in the new pickups is the  6.0L Vortec gas V8 with variable valve timing and other state-of-the-art technology that brings power output to 353hp and 373 lb/ft of torque.  Fuel economy, although not certified, is said to be in the neighborhood of 18mpg on the highway and near 14 in town.

Such fuel numbers—and the feel of a much more powerful engine from a stop—is a direct result of an all-new 6-speed automatic that replaces the 4L80 4-speed of yesteryear.

The Hydra Matic 6L90 has a stump-moving 4.03:1 Fist gear and a 6.04:1 overall ratio spread (the 4L80 was 3.31:1) – including a double overdrive that helps deliver an excellent balance of performance and fuel economy.

Equally nice is the new six-speed offers manual gear selection with tap up/tap down shift control, a Tow/Haul mode, and smart Grade Braking, all which make trailer towing and hauling big loads a breeze.


But the real driving fun comes when you get the optional ($8,500) Duramax/Allison diesel package. The new Duramax 6.6L turbo-diesel is the most powerful diesel in the 3/4- and 1-ton pickup market with 365 horsepower and 660 lb.-ft. of torque.

The base engine for the ’07 Heavy Duty pickups is the 353hp, 6.0L Vortec V8 backed by an all-new Hydra-Matic 6L90 6-speed automatic with either 3.73 or 4.10 axle ratios. The upgrade ($8,500) is the 6.6L 365hp Duramax diesel and Allison 1000 six-speed automatic with 3.73 axle ratios. The base engine for the ’07 Heavy Duty pickups is the 353hp, 6.0L Vortec V8 backed by an all-new Hydra-Matic 6L90 6-speed automatic with either 3.73 or 4.10 axle ratios. The upgrade ($8,500) is the 6.6L 365hp Duramax diesel and Allison 1000 six-speed automatic with 3.73 axle ratios.

GM’s torque monster is also one of the cleanest. My seatmate during one of the towing segments, Charlie Freese, the Executive Director of GM Powertrain and the hands-on-expert of the “new” Duramax, says the upgrades bring it 2010 emissions standards all the while improving fuel economy and power.

Its cleanliness is quite evident when you’re following one of the new diesel-powered GMs; there’s not a hint of black smoke, nor any hint of unburned diesel fuel.

The new Duramax provides a 90-percent reduction in particulate matter and a 50-percent reduction in NOx (compared with current standards), meeting a new federal government emissions mandate that applies to all diesel engine manufacturers.

Freese explains such clean running comes as a direct result of computer-designed combustion chambers to burn the fuel more efficiently—and the incorporation of an ungainly-looking exhaust system that marries a bulky catalytic converter, muffler and particulate filter system to a very weird-looking tailpipe.

Freese explained the odd-shaped exhaust tip greatly reduces the 800-degree exhaust that blows out the particulate filter when it burns off the soot, or “regenerates,” while you drive down the road.

Without the odd-looking, air-cooled tailpipe you’d probably burn the paint off the fender and roast anyone standing next to the exhaust tip when the regeneration process begins.

As for the fuel economy, Freese says in general a turbo-diesel such as the Duramax will be about 25-percent more fuel efficient than a comparable gas engine when unburdened, and up to 70-percent more fuel-efficient when loaded down and running at higher elevations.

Trailer towing is an easy task with the new GM HD diesel pickups.Trailer towing is an easy task with the new GM HD diesel pickups.

That said, we’d expect to see the new Duramax deliver about 22mpg on the open road (unladen, of course) and close to 15 in the city. Not bad for a truck with a curb weight knocking close to 7,000 pounds.


 What hasn’t changed in the diesel powertrain is the renowned Allison 1000 six-speed automatic transmission.

The Allison can be manually shifted if so desired, and it employs grade-braking and other features that quickly match driving conditions to vehicle speed, engine rpm and load.  

Speaking of load, if you need to haul your heavy off-road adventure toys the new GM heavy duty pickups are up o the task. All of the new Heavy Duty’s are equipped with a 2 ½-inch receiver hitch instead of the more conventional 2-inch found on the ½-tons.

That means 4Ă—4 models with the gas engine can pull toy haulers and boats up to 12,400 pounds on the hitch ball without using a weight-distribution hitch. The diesels can tow up to 13,000 pounds, or use a 5th wheel and the HDs can pull trailers weighing up to 16,700 pounds.

Lest we mention the gas-powered Heavy Duty pickups have a maximum gross combined weight rating (GCWR) of a whopping 18,500 pounds, making the new GMs the towing leader in the Âľ and 1-ton pickup class powered by a small-block V-8.

Overall impressions of the GM’s: refreshed and refined heavy duty pickups resulting in a  sweet-driving package.

Add in the option of getting the Z71 Off-Road 4×4 suspension that’s new to the HDs and you can rest assured that if you are an off-road adventurer or construction company owner who needs a strong, refined truck for work—and an equally strong, yet comfortable toy hauler for those well-earned days off—you’d be hard-pressed to find anything better in 2007.

I imagine that’s what the guy in the slow lane is thinking right now as I roll past him with my big Ranger saltwater boat casting a quick-moving shadow across the sides of his new F-250 Super Duty.—Bruce W. Smith