2004 Gmc Sierra 1500 Denali on 2040-cars

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GM recalls 740,000 vehicles over daytime running light issue

General Motors is recalling over 740,000 vehicles due to a daytime running light issue that causes all of the affected cars to run afoul of Federal Motor Vehicle Safety Standards. Vehicles affected by this recall are spread across many of GM’s brands. Models include the 2020-2023 Cadillac CT4 and CT5, 2021-2023 Buick Envision, 2022-2023 Cadillac Escalade and Escalade ESV, 2022-2023 Chevrolet Silverado 1500, Suburban, Tahoe and 2022-2023 GMC Sierra 1500, Yukon, and Yukon XL. GM says that the daytime running lights may remain on in these cars when the headlights are activated. This is a problem, because FMVSS rules require that the daytime running lights deactivate once the headlights turn on. If the DRLs remain on, GM says that could result in additional glare, thereby increasing the risk of an accident. The cause of this failure to deactivate the DRLs comes from body control module software that “under a combination of certain pre-conditions, could fail to deactivate the DRLs,” according to GM. Other GM vehicles were tested, but due to a difference in software or hardware, they remain unaffected. If this is reminding you of another recent GM recall, youÂ’d be right, as GM recalled another 340,000 vehicles for the same issue last month. After that original issue was found within GM, the company began looking into its other cars to determine if the population was larger than originally thought. GM found the additional vehicles included in todayÂ’s recall have the problem. The fix will either be via an over-the-air update or it will require you to bring the vehicle into a dealer for a software update, depending on which vehicle you have. Owner notification letters letting folks know what is necessary are currently scheduled to go out on January 23, 2023. Related video: Cadillac Escalade Infotainment Review

Redesigned 2021 GMC Yukon gets a diesel, AT4 model, Denali-exclusive interior

GMC's most robust family hauler is getting a complete redesign for the 2021 model year, including a new, off-road centric AT4 model, an upscale interior exclusive to its luxurious Denali model, an available air suspension, and, last but not least, a diesel engine.  With Americans obsessing over trucks, it's no surprise that GMC is going hard with its AT4s-for-everybody strategy; the Yukon is no exception. This will be the first model year for the new trim on GMC's largest SUV. This off-road model gets all the goodies you'll need to veer off the beaten path with confidence, including an extra 2.0 inches of ground clearance with the adaptive suspension option (more below), a two-speed transfer case, standard Goodyear all-terrain tires, an off-road mode for GMC's "Traction Select" drive mode system, hill descent control, and some extra underbody skid plates. Since GMC is a premium brand, even the AT4 gets some luxury appointments, such as a heated steering wheel, heated and ventilated front seats, and heated outboard second-row seats. The interior is also adorned in black leather with tan accents and "AT4" embroidery in the seat backs.  Speaking of premium, GMC will introduce an air-ride adaptive suspension with an off-road ground clearance mode as a late-availability option for several Yukon models, and this feature will be included on the Denali trim.  The Yukon and Yukon XL are GMC's variants of Chevrolet's full-sized SUVs, the Tahoe and Suburban. Their fundamental body-on-frame architecture is also shared with GM's half-ton pickup trucks, and thanks to that common engineering, they can also share powertrains. That's normally just a trivial side note when it comes to a new GM SUV announcement, but this time around, it's a bit more meaningful thanks to the introduction of a new light-duty, inline-six diesel in GM's truck lineup last year.  Yep, that means that for 2021, like the Tahoe and Suburban, the Yukon is getting a diesel option. The 3.0-liter Duramax makes the same 277 horsepower and 460 pound-feet of torque as it does in GM's trucks.  GMC's standard engine is still the 5.3-liter V8 that makes 355 hp and 383 lb-ft of torque. The 6.2-liter V8 is also an option like before, producing 420 hp and 460 lb-ft of torque. All engines come with a 10-speed automatic and a choice of rear- and four-wheel drive.

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!"