2001 Gmc Sierra Extended Cab 4x4...well Maintained--very Nice 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.

'Killing a Duramax' Gale Banks YouTube series methodically tunes a diesel to death

Learning or perfecting a skill by watching YouTube videos is known as attending YouTube University. GM Authority picked up on one of the video site's more fascinating courses, hosted by Gale Banks; in a fair world, he should be referred to as Professor Banks when it comes to diesel engines and truck tuning. A few months after GM introduced the updated L5P 6.6-liter Duramax diesel V8 in the 2020 Chevrolet Silverado HD and GMC Sierra HD that ships with 454 horsepower and 910 pound-feet of torque, Banks decided he wanted to methodically tune the engine to death. The purpose of the resulting series, called "Killing a Duramax," is to push more power out of the engine in order to discover which parts break and when — or, as Banks puts it, force-feed the Duramax "until the crank hits the street and the heads hit the hood." With that knowledge, Banks can figure out all the weak points on his way to building what he calls a "Superturbo," that being a supercharged, twin-turbo race engine with more than 1,000 hp. What makes the series fascinating is Banks' knowledge, paired with the company's comprehensive iDash engine monitoring system that keeps tabs on a glut of parameters every step of the way. So for instance, you get Banks explaining the differences between inches of mercury and barometric pressure, how those are different from the water content of the air measured in grains, then showing those readouts on the iDash, then explaining in detail how they affect the air density in the Duramax system. The stock Borg-Warner variable turbo gets a lot of airtime — Banks accuses it of being "out to lunch" because he feels it's the weakest link on the engine. That turns into a turbo teardown and a deep explanation of performance pitfalls, such as when air pressure on the turbine begins to diverge from the boost pressure coming from the compressor. Banks says he can keep close tabs on where power's coming from, because the iDash monitors the horsepower contribution provided by the ambient air, the turbo, and the intercooler separately. The major changes so far are a stouter Precision 7675 turbo and TurboSmart wastegate (episode 5), a twin intake (episode 6), a custom liquid-cooled intercooler from a marine engine, a new GM oil cooler and synthetic oil (episode 10), and new injectors (episode 11).

2019 GMC Sierra AT4 gives Raptor and Ram a new off-road rival

The 2019 GMC Sierra AT4 blends off-road hardware into a modern, thoroughly updated pickup truck that doesn't skimp on power, luxury, or safety equipment. From its higher suspension setup to its available carbon-fiber cargo bed and the new MultiPro tailgate, the 2019 Sierra AT4 is a direct shot across the bow — or cargo beds, if you prefer — of staunch rivals like the Ford F-150, Dodge Ram and Toyota Tundra. Revealed tonight in New York City, ahead of this week's New York International Auto Show, the truck may seem to be in a strange setting. Then again, with the amount of tire-swallowing potholes currently scattered around the Big Apple, a rugged truck like the Sierra AT4 could be the perfect vehicle for either off-road excursions or an especially bumpy commute. Riding two inches higher than the standard 2019 Sierra, the AT4 comes with standard features like all-wheel-drive with a two-speed transfer case, locking rear differential, Rancho monotube shock absorbers designed specifically for off-roading, along with skid plates and 18- or 20-inch alloy wheels fitted with all-terrain tires or optional, mud-loving Goodyear Wrangler Duratecs. Hill descent control and GMC's Traction Select system are also standard. The latter of these two lets the driver choose between preset drive modes, suitable for various types of terrain and weather conditions. The system then adjusts throttle response, shift points, and the electronic stability control according to each mode. Related: 2018 GMC Sierra 1500 buying guide "The 2019 Sierra AT4 is designed for the customer who wants an elevated presence on the road and the capability to venture off life's beaten path," said Duncan Aldred, vice president of Global GMC. "It's also the beginning for the AT4 brand, which will be seen on every vehicle in our lineup in the next two years." Based on the new 2019 Chevrolet Silverado, the GMC Sierra (including the AT4 model) looks to stand out from its corporate cousin in terms luxury touches, along with some subtle exterior details. For the AT4, these visible differences include a body color grill surround and bumpers. Meanwhile, the inner grille, front fog-lights and faux fender vents feature a black-chrome finish. It's not flashy, which is probably exactly what GMC wanted for its upscale truck. The standard engine is a 5.3-liter V8, though buyers can choose an optional 3.0-liter turbo-diesel inline-six or 6.2-liter V8.