2021 Sierra Denali on 2040-cars

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GM's fullsize SUVs boost highway mileage by nearly 10 percent

We met the redesigned 2015 versions of the Chevrolet Suburban and Tahoe, and the GMC Yukon and Yukon XL at the 2013 LA Auto Show. Improved gas mileage numbers have been announced to go along with the improved exteriors and interiors, with city mileage improving by seven percent and highway mileage going up by nearly ten percent; you'll now get 16 miles per gallon in the city and 23 on the highway.
The only applies to models with the 5.3-liter engine, though, not the premium Yukon Denali and Yukon XL Denali SUVs with the 6.2-liter motor. Still, the 5.3 gets you more power than previously, with 355 horsepower and 383 pound-feet of torque underfoot, on top of the improved fuel economy numbers. The 6.2-liter sticks with official mpg ratings of 15 highway, 21 city. There's a brief press release below with words straight from the horse's mouth.

GM opens official investigation into C8 Corvette transmission leaks

In March 2020, a month after Chevrolet began customer deliveries of the 2020 C8 Corvette, a GM dealer technician created a Reddit thread about a leaking gearbox in a Corvette with 32 miles. That car hadn't even been sold yet. Since then, as a search of "C8 Corvette transmission leak" shows, it's been tales of woe for some owners. Something in the Tremec TR-9080 transaxle in the back of the mid-engined Corvette doesn't work as it should, the fault able to cause codes that the transmission needs service, or that the driver needs to shift to park. In some cases, the battery would die because of follow-on issues after the initial transmission code, that code preventing the car from powering down. As Autoevolution reports, GM filed paperwork with the National Highway Traffic Safety Administration in August to look into what's going on. Between forum threads and GM's investigation document, there are several issues mentioned. The most common appears to be the dual-clutch transmission leaking fluid due to gasket failures like the one suffered by one owner at 858 miles, and another for an owner currently enduring a second leaking transmission. The Midengined Corvette Forum reported that Chevy engineers redesigned the TR-9080 pan, fitting Corvettes with the new unit at some point in the 2021 model year. The original pan was stamped steel unit affixed to the engine with two studs and 13 bolts, plus "reinforcement plates." The updated pan is said to be a cast aluminum unit affixed with two studs and 17 bolts, omits the reinforcement plates, and gets a new machined new groove around its edge to seat the gasket seal. The GM paperwork now at the NHTSA mentions a P1789 code, and says one reason for it could be "debris on the park position sensor magnet causing an incorrect position reading to the TCM." This might be caused by another issue mentioned in forums, which is clogged transmission filters. GM gives instructions for returning transmission filters to the company, and a poster on one forum said the Corvette tech at the dealer where he bought his Corvette told him the automaker "requires every used transmission filter to be returned to GM."  Whatever's going on, the problems haven't stopped, and they go beyond the P1789 code. Over the weekend, a 2022 Corvette owner posted on Corvette Forums that he got a check engine light on his car after just 850 miles.

2024 GMC Hummer EV 3X Pickup gets a range boost

The 2024 GMC Hummer EV 3X Pickup is getting an update for more range in the new model year. Instead of 355 miles, the new long-range version of the 3X Pickup will go 381 miles. Note that you need to option the 24-module battery pack to get this range figure. However, if you go for the standard 20-module battery pack, GMC says range is improved for 2024, as well. The GM-estimated figure goes from 329 miles for 2023, all the way up to 359 miles for 2024. You should also note that acceleration times are different depending on battery pack, too, as the longer-range model does 0-60 mph in 3.0 seconds versus the 3.5 seconds of the standard range version. The other big choice you’ll need to make is whether or not you tack on the “Extreme Off-Road Package.” This adds 18-inch wheels wrapped by 35-inch mud-terrain tires, four addiitonal underbody camera views for a total of 18, front e-locker with rear virtual locking differentials, heavy-duty ball-spline half-shafts along with more skid plates and underbody shielding. WeÂ’ll also note that range suffers as a result of this equipment. GM only provides the range figure for the upgrade 24-module pack, and it goes down from 381 miles to 359 miles. GMC says the 2024 Hummer 3X Pickup will go on sale to reservation holders this fall and start at $106,945, including the destination charge. Related video: