• HOME
• 
• AUTO LISTINGS
• 
• FINANCE
• 
• NEWS
• 
• DIRECTORY
• 
• REVIEWS
• 
• FORUM
• 
• BLOG
• 

2006 Chevrolet Silverado 2500 HD Road Test

Duramax/Allison Partnership Prove Might is Right

The hiss generated by the high-pressure, variable geometry turbocharger force-feeding GMs massive 6.6-liter (403 cu-in) Duramax diesel V8 gave my prodigious Silverado 2500HD 4X4 tester the acoustics to match its stunning torque rating of 650 pound-feet. Accompanying the mountain of torque in the new-for-2006, larger Duramax is 360 horsepower. Thats the kind of brawn needed to pull 5th wheel homes and horse trailers through mountain passes without holding-up traffic like a cork in a bottle. With so much pulling power at one end and dead weight at the other, an automatic transmission was often the weak link in an otherwise very strong chain. For 2006, GM has hardened the susceptible weak link by bolting

Silverado HD is a truck thats at home towing horses, trailers, boats, and just about anything else that can to be moved. (Photo: Rob Rothwell, American Auto Press)

a 6-speed Allison-manufactured autobox to the rear of its "bruiser," Vortec 8100 (gas) and Duramax 6600 (diesel) powerplants.

The Duramax/Allison partnership is definitely the Silverado highlight this year. The big Duramax was engineered to pump-out segment-leading torque while delivering 15 to 20 percent better fuel economy than GMs current 6.5-liter turbo diesel, although official figures

A real big engine with a real big thirst for diesel. But imagine, what would consumption have been like on a gasoline engine? (Photo: Rob Rothwell, American Auto Press)

have yet to be released. During my heavy-footed time behind the wheel, the vehicles driver information screen displayed an average fuel economy rating of 13.3 miles per gallon. Despite these pocketbook-crushing results, GM claims to be setting new industry standards for fuel efficiency, diesel power and performance in the heavy-duty pickup class with the Duramax 6600.

According to GM, not only is their new "oiler" more efficient than previous GM diesels, its

Duramax diesel is quieter than before, but a symbol of brute force nevertheless. (Photo: Rob Rothwell, American Auto Press)

quieter too. Noise, vibration and harshness (NVH) figures, based on GM literature, are comparable to similar-sized gasoline engines. After spending a week behind the wheel of my tester that included both city-traffic plodding and open highway cruising, Im not prepared to validate GMs NVH claim. From ignition to shutdown there is no doubt that the Duramax 6600 is drinking diesel; nonetheless I was impressed with the civility of the big workhorse. This engine is a pleasure to administer.

Thanks to revised glow plugs, the new Duramax starts instantly. Once underway it pleases

Cold weather not a problem thanks to new glow plugs in the engine. (Photo: Rob Rothwell, American Auto Press)

with delightful-for-a-diesel operational refinement while delivering abundant power in a smooth, progressive manner - and boy can it kick. I was quite surprised by the Silverados take-off punch and its no-holds-barred passing ability. After the Allison gearbox takes a moment or two to insert the most suitable cog, the big truck storms ahead with unrelenting ferocity. With a range of six gears and 650 foot-pounds of torque at only 1,600 rpm, there were simply no flat spots in the acceleration continuum to impede the hastening of my testers 5,883 lb curb weight. With shift-points coming at 3,200 rpm when the pedal is on the metal, the more gears available, the better.The 6-spd Allison transmission is probably the most technically innovative part of this truck. (Photo: Rob Rothwell, American Auto Press) /> With its half dozen cogs, the Allison tranny is worthy of a review dedicated solely to its sophisticated technology. Rather than befuddle readers - and myself - with such minutiae, I will hit the aspects important to most purchasers and leave the techno-babble to those with plenty of time to search-out the finer details. As with modern automatic gearboxes, placing the shifter in "D" relieves the driver of any need to participate in shifting gears. The Allisons Adaptive Shift Control feature will select the appropriate gear by analyzing engine torque and vehicle speed. In doing so, it will minimize unnecessary up-shifts and down-shifts. A Tow/Haul mode can be instantly activated with a button situated

Simple push-button transfer case is easy to use. (Photo: Rob Rothwell, American Auto Press)

at the end of the gearshift stalk. The Tow/Haul mode alters shift patterns in order to maximize the engines efficiency in both pulling and braking. When the Tow/Haul function is activated, Grade Braking is also engaged. In an effort to maintain the vehicles speed when descending a grade, the electronic program inserts a lower gear to improve engine baking, even when the truck is operating under Cruise Control.

Perhaps the most useful to drivers wanting more human input into shift patterns is Allisons Range Selection Mode, which enables manual, electronic shifting between the six gears. Positioning the shift lever in "M" activates a small rocker switch near the end of the gearshift stalk. The button corresponds with a small LED readout in the instrument panel depicting gears 1 through 6. Moving throughout

Bouncy ride when the beds empty, but when loaded, the ride ought to quiet down. (Photo: Rob Rothwell, American Auto Press)

the gear range is as easy as rocking the button up or down. The Range Selection Mode makes manual shifting as easy as it gets, which pretty much describes driving the bulky Silverado on pavement or off, thanks to its shift-on-the-fly four-wheel-drive (4WD) capability. When things get severely ugly, engaging a low-range set of gears while locked in 4WD is simply another button-push away. When the mucky stuff gives way to asphalt, the Silverado quickly softens its rugged demeanor.

At posted highway speeds and slightly above, my tester generated very little road and wind noise, especially for a hulking pickup truck. Regardless of speed the big rig remained stable and steady while encountering side winds and undulating pavement, however, over sharp bumps the firmness of its real leaf springs induced a choppy, somewhat bouncy ride. When compared to the harsh ride

Leather seats: a comfort feature, but also a convenience feature. Its much easier to wipe down than cloth. (Photo: Rob Rothwell, American Auto Press)

of other heavy-duty 3/4 ton 4X4 pickups I have contended with, the Silverado has no apologies to make. Adding a little weight to the empty box would undoubtedly excise some of the ride discomfort, but even without the weight advantage, the Silverado 2500HD is a tremendously comfortable highway cruiser. On smooth pavement it loafs along in 6th gear turning well under 2,000 rpm to maintain typical highway speeds. Much of the Silverados comfort can be attributed to its expansive cabin and first-rate seating.

The heated, leather-upholstered captains chairs in the fore cabin of my tester were wonderfully supportive and widely adjustable, easily accommodating most driving positions, although the inclusion of a left foot dead pedal would increase leg comfort and enhance the drivers connection to the vehicle. A large center console and storage bin separates the comfy front perches. Less-positive comments pertain to the out-dated instrument

The Silverado has plenty of space for five burly people inside its crew cab. (Photo: Rob Rothwell, American Auto Press)

panel facing the driver; yes it clusters together a full complement of gauges but not within a modern setting such as in GMs new line of Yukon and Suburban SUVs. The European-influenced dashboard in those new offerings do away with the plastic framing and sharp angles that define the Silverados tall, upright dashboard. Nonetheless, theres nothing missing in the Silverados rendition other than class and visual appeal.

Page:  1

AUTOMOBILE REVIEWS BY MAKE

Acura  Audi   Bentley   BMW   Buick   Cadillac   Chevrolet   Chrysler   Daewoo   Dodge   Eagle   Ferrari   Ford   Geo   GMC   Honda   Hummer   Hyundai   Infiniti   Isuzu   Jaguar   Jeep   Kia   Lamborghini   Lexus   Lincoln   Lotus   Maserati   Mazda   Mercedes-Benz   Mercury   MINI   Mitsubishi   Nissan   Oldsmobile   Plymouth   Pontiac   Porsche   Saab   Saturn   Scion   Subaru   Suzuki   Toyota   Volkswagen   Volvo