2007 Gmc Sierra 3500 Slt on 2040-cars

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GM 6.2L EcoTec V8 rated at 21 mpg by the EPA

General Motors is already laying claim to best-in-class power for its new 6.2-liter V8 that will be offered in the 2014 Chevy Silverado and GMC Sierra this fall, and now it has released fuel economy numbers for the big engine. Available as an option on the Silverado LTZ and High Country (shown above) models as well as the the Sierra SLT and Denali trims, the 6.2L EcoTec3 V8 will return 15 miles per gallon in the city and 21 mpg on the highway on rear-wheel-drive trucks; these numbers drop by one mpg each on four-wheel-drive models.
These estimates are in addition to the engine's 420 horsepower, 460 pound-feet of torque and max trailering capacity of 12,000 pounds, and considering all that power it's not terribly far away from the fuel economy of GM's equally new 4.3-liter V6 and its rating of 18 mpg city and 24 mpg highway. This announcement comes just days after a report indicated that GM is unable to keep up with the demand of the 5.3-liter V8 in the fullsize Chevy and GMC trucks due to supplier issues. GM's official press release for the 6.2-liter V8's fuel economy is posted below.

Diesel Power finds the ultimate modified oil-burner

For nine years, Diesel Power magazine has run the Diesel Power Challenge, this year's grindfest being "a week-long torture test that features seven events, nine trucks, 8,000 horsepower, and nearly 15,000 pound-feet of torque." The road to being crowned "the most powerful truck" starts with a dyno run, and then continues through the completion of a CDL-style obstacle course, an eighth-of-a-mile drag race while towing a 10,000-pound trailer, a quarter-mile drag race without a trailer, a fuel economy test in the mountains and finally a sled-pulling test through a 300-foot-long packed-mud pit.
What kind of trucks get into such a fight? Last year's winner, for instance - who upgraded his truck this year to prove he didn't "luck into the win" - drives a 2008 Ford F-250 Super Duty with a 6.4-liter Power Stroke V8 upgraded with a custom intake, Elite Diesel triple turbos and a two-stage nitrous system. Another competitor has a 2005 Dodge Ram 2500 powered by a 5.9-liter Cummins inline-six, upgraded with Garrett turbos, dual-stage nitrous, a seven-inch exhaust stack and twin fans built into the bed to cool the Sun Coast Omega transmission. The numbers on that truck: 1,255 horsepower, and 2,063 pound-feet of torque at the wheels. Naturally, as the image above might suggest, things don't always end well.
You'll find all five videos covering this years challenge below. A scene in the dyno video sums it all up perfectly: a competitor leaves his nitrous on too long and the crew is treated to some ominous poppings, he leans out the window, throws both hands up and shouts, "Amer'ca!"

2015 Sierra All Terrain HD looks ready to hit heavy-duty trails

GMC is getting its heavy-duty trucks ready for the mud this summer with its All Terrain package for the Sierra 2500HD and 3500HD. Meant to blend style, tech and ruggedness, the pack includes a lot of extra chrome outside and an off-road package underneath.
The 2015 Sierra All Terrain HD trucks naturally come standard with four-wheel drive with an electronically controlled transfer case to handle things in the dirt. The Z71 off-road package is also standard, which includes Rancho twin-tube shocks, hill descent control and a skid plate. To add some style when off the beaten path, the pack includes chrome trim on the mirror caps, lower bumper and grille surround, plus LEDs around the headlights and 18-inch wheels (20-inchers are optional on the 2500HD). The 3500HD also gets chrome, adjustable outside camper mirrors. The interior receives a technology upgrade thanks to the standard rearview camera and IntelliLink infotainment that can act as a Wi-Fi hotspot through OnStar 4G LTE, read text messages and includes Siri Eyes Free for iPhone users.
The All Terrain package goes on sale on both trucks this summer and is offered on either the SLE or SLT trim levels in double cab and crew cab models. The standard engine is the 6.0-liter V8 with 360 horsepower and 380 pound-feet of torque, but the Duramax 6.6-liter, diesel V8 with 397 hp and 765 lb-ft is also available. The gas engine is mated to a Hydra-matic six-speed automatic, and the diesel uses an Allison six-speed automatic. Scroll down to read the full announcement about these heavy-duty off-roaders.