2008 Gmc 3500hd Slt Regency Edition 4x4 Duramax Diesel 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.

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!"

Ford F-150, Chevy Silverado, Toyota Tundra flunk IIHS headlight test

The Insurance Institute for Highway Safety put pickup truck headlights to the test and found that the majority of them were equipped with subpar units. The 2017 Honda Ridgeline was the only truck to earn a rating of "good." The large pickup truck test was comprised of the: 2016 to 2017 GMC Sierra, 2017 Nissan Titan, 2016 Ram 1500, 2016 to 2017 Chevrolet Silverado, 2016 to 2017 Ford F-150, and 2016 to 2017 Toyota Tundra. The Sierra's headlights earned a rating of "acceptable," the headlights found on the Titan and Ram 1500 were found to be "marginal," and the ones on the Silverado, F-150, and Tundra were rated as "poor." IIHS claims the F-150 was the most disappointing out of the large pickup trucks as both its halogen and optional LED headlights failed to provide adequate visibility during testing. The Ridgeline (which earned a "good rating"), is usually considered a midsize or small truck, though IIHS included it in the field of large pickups. The headlights on the 2016 Chevrolet Colorado, 2016 GMC Canyon, 2016 Nissan Frontier, and 2016 to 2017 Toyota Tacoma, which made up the small pickup truck group, all earned a rating of "poor." The IIHS claimed the Colorado had the worst headlights of any truck that was tested, as the base vehicle's units were only able to illuminate up to 123 feet in front of the car. The Ridgeline's headlights, for reference, were able to illuminate up to 358 feet in front of the vehicle. To conduct its test, the IIHS utilizes a special tool to measure how far light is projected out of the headlights in different driving situations. The trucks' headlights were tested in a straight line and in corners, while vehicles with high-beam assist were given extra praise. The headlights on the pickup trucks also mimic the testing that was done on small SUVs and cars earlier this year. Next year, automakers will need to fit their vehicles with headlights that earn a rating of either good or acceptable to earn the IIHS Top Safety Pick+. Related Video: