2004 Gmc 2500hd Duramax Diesel Extended Cab 4x4 on 2040-cars

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2018 GMC Acadia with 'Christmas Aero' modification gets in the wind tunnel

Tis the season of "Big" - big cheer, big parties, big bowls of eggnog, big decorations, and when it comes to your family hauler, big drag. Festive drivers who festoon their crossovers, minivans, and SUVs with wreaths, Rudolph noses, fuzzy antlers, and rooftop Christmas trees undo the years of work that car engineers devote to fractional gains in fuel economy. To put numbers to such fuel-guzzling madness, GMC started with a 2018 Acadia, optioned it with the Xmas Aero Package - both Standard and Plus versions - put it in Lockheed-Martin's wind tunnel. The resulting dip in fuel economy results probably won't surprise anyone who's used a roof rack - or, for that matter, their car's air conditioning. However, it might surprise you to find out which seemingly substantial decoration had no effect, and which seemingly innocuous decoration was about twice as bad as running the A/C on its Mr. Freeze setting. Check out the brief video above for the results. And consider placement of that bow carefully.

Fullsize GM SUVs have a problem that's making owners sick

Some fullsize SUV owners are getting sick, thanks to a buffeting and vibration problem in 2015 model year examples of the Chevy Tahoe and Suburban, Cadillac Escalade, and GMC Yukon. According to owners' complaints to the National Highway Traffic Safety Administration, the issue can vary from an annoying vibration inside the cabin to an experience so severe that it leads to dizziness and headaches. General Motors is aware of the complaints, but the fix isn't so simple. According to spokesperson Tom Wilkinson to Autoblog, the company "has been tracking this issue for a while." The problem has a fairly low incidence rate, but when it does occur the issue can be "uncomfortable and annoying for owners." There's no precise cause for the issue, Wilkinson claims, and in some cases, simply balancing the tires or changing the door seals can make it go away. However, not all of the fixes are so simple. AutoGuide dug deep into the problem and discovered a GM preliminary information bulletin that advised dealers to remove the headliner and to check the roof's bonds to the bows that go across the vehicle. However, that document included a note that the solution might not entirely eliminate things. According to AutoGuide, adding Dynamat insulation to the roof sometimes helped the problem. A GM spokesperson also told AutoGuide the company fixed the problem at the end of the 2015 model year, and didn't go into any more detail. This roof issue seems linked to some of the worst droning in these SUVs. According to one complaint from a 2015 Suburban owner to NHTSA: "Roof will not remain attached to the roof bows. This causes the buffeting similar to a window being down when all are up. The results span from annoying to painful." A 2015 Yukon owner claims to have another alleged cause for the problem in a NHTSA complaint from February 2015. This person brought their SUV to the dealer seven times over the course of four weeks for vibrations. The dealer replaced the driveshaft, suspension components, and more, but nothing worked. According to an engineer to the service adviser: "In an effort to prevent roll overs, they designed the frame and body mounts too stiff. There are 40 engineers working on issues, they have no solutions that work across the board." Wilkinson told Autoblog that GM is working with customers on an individual basis to rectify things. Since these are newer vehicles, dealers should also fix the problem under warranty.

What the electric Hummer's size and weight means for its efficiency

The 2022 GMC Hummer EV Edition 1. Tim Levin/Insider If you think driving a pint-sized Nissan Leaf is as good for the planet as driving a huge electric Hummer, think again.  The GMC Hummer EV uses significantly more electricity than other EVs, meaning it produces more pollution upstream.  The electric Hummer weighs 9,000 pounds and its battery weighs as much as a Honda Civic. The new electric Hummer rolls through town without a deafening engine rumble or a cloud of toxic fumes, but it doesn't exactly tread lightly.  The colossal truck weighs an astonishing 9,000 pounds. (Think two Toyota Tacomas, three Honda Civics, or 24 Shaquille O'Neals.) Moreover, the GMC Hummer EV is in many ways a supersized gas guzzler for a new era. It repackages many of the same flaws of hulking SUVs and trucks of years past — and proves not all zero-emission cars are created equal. EVs can be energy guzzlers too On the whole, electric cars use less energy than gas-powered ones. But they aren't all equally efficient.  No surprise here: The Hummer needs more electricity than any other EV on the market to move its elephantine frame. The Environmental Protection Agency rates the pickup at 47 MPGe (miles per gallon of gasoline-equivalent). For comparison, the Tesla Model 3 sedan is nearly three times as efficient, earning a rating of 132 MPGe. The Ford F-150 Lightning, another electric truck, gets 70 MPGe.  This has real consequences: Since the US gets 61% of its energy from oil, coal, and natural gas, the more electricity a car needs, the more pollution it creates upstream.  As the Union of Concerned Scientists put it: "Both EV cars and trucks are much cleaner than their gasoline counterparts, but electric trucks are responsible for more global warming emissions than electric cars simply because trucks are larger and heavier."  The 2022 GMC Hummer EV Edition 1. Tim Levin/Insider The Hummer EV is also resource-intensive to manufacture, requiring a ginormous (and weighty) battery to give people the 300-plus miles of range they desire. You could produce three Chevrolet Bolts with the same battery cells consumed by one Hummer.