2003 Gmc Yukon Xl 1500 Denali 4-door 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.

GM confirms 2015 Silverado, Sierra to get 8-speed automatic

When viewed alongside the next Ford F-150 and the Ram 1500, there is one thing that seems to be missing from the Chevrolet Silverado and GMC Sierra. Where the F-150 will rely on turbocharging and aluminum architecture and the Ram sports an eight-speed automatic and an air suspension, the General Motors twins lack a big, calling-card feature. They're very good, very refined trucks, but one could argue that they're not terribly innovative.
And while it might not be as flashy a feature as air suspension or a lightweight skin, the Silverado and Sierra will get their own eight-speed automatic for 2015, a transmission that will be paired with the company's Ecotec3 6.2-liter V8. The new cogswapper will also find its way into the GMC Yukon Denali, but for now, there's no indication why the Cadillac Escalade, Suburban, Tahoe and standard Yukon are being left out.
According to GM, the new gearbox is about the same size and weight as the current Hydra-Matic 6L80 six-speed. By the time the new powertrain combination enters production late this year, the EPA will almost certainly have gotten around to certifying the vehicles' fuel efficiency. Until then, feel free to speculate. The current Silverado with the 6.2 and six-speed auto returns 14 miles per gallon in the city and 20 on the highway. How much do you think the eight-speed will improve those figures? Scroll down for the official press blast from General Motors, and then head into Comments.

Chevy Silverado, GMC Sierra 4.3-liter EcoTec3 V6 nets 18 mpg city, 24 highway

There is no doubting that fuel economy has become an important factor in the highly competitive fullsize truck market, with the Ford F-150 EcoBoost V6 and Pentastar V6-powered Ram 1500 setting quite a precedent in recent years. Now it's General Motors' turn. The General has just announced that the new base V6 used in the 2014 Chevrolet Silverado and GMC Sierra 1500 models will return an EPA-estimated 18 mpg city and 24 mpg highway in two-wheel drive trim, regardless of cab configuration.
While these figures don't go so far as to earn GM any "best-in-class" fuel economy claims (thanks to the 25-mpg Ram 1500 HFE), this new 4.3L EcoTec3 V6 does edge the F-150 and Toyota Tundra while boasting best-in-class numbers for torque, payload and towing capacity among six-cylinder rivals. This all-new engine produces 285 horsepower and 305 pound-feet of torque, and it gives the 2014 Silverado and Sierra the highest towing rating among standard V6 models with a 7,200-pound towing capacity - besting the Ram by 700 pounds, the base F-150 by 1,100 pounds and coming within 200 pounds of the V8-powered Nissan Titan. Scroll down for the official press releases from Chevrolet and GMC.