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Even if GM does close all 5 of those plants, it'll still have too many

DETROIT — General Motors' monumental announcement on Monday that it will close three car assembly plants and two powertrain plants in North America and slash its workforce will only partially close the gap between capacity and demand for the automaker's sedans, according to a Reuters analysis of industry production and capacity data. Sales of traditional passenger cars in North America have been declining for the past six years and are still withering. After GM ends production next year at factories in Michigan, Ohio and Ontario, it will still have four U.S. passenger-car plants — all operating at less than 50 percent of rated capacity, according to figures supplied by LMC Automotive. In comparison, Detroit-based rivals Ford and Fiat Chrysler Automobiles will have one car plant each in North America after 2019. The Detroit Three are facing rapidly dwindling demand for traditional passenger cars from U.S. consumers, many of whom have shifted to crossovers and trucks. Passenger cars accounted for 48 percent of retail light-vehicle sales in the United States in 2014, according to market researchers at J.D. Power and Associates. This year, sedans will account for less than a third of light vehicle sales. That shift in turn has left most North American car plants operating far below their rated capacities, while many SUV and truck plants are running on overtime. The collapse in passenger-car demand is a challenge for nearly all automakers in the United States, including Japan's Toyota and Honda, which have the top-selling models in the compact and midsize car segments. Toyota executives said last month they are evaluating the company's U.S. model lineup. But Toyota also plans to build compact Corolla sedans at a new $1.6 billion factory it is building in Alabama with partner Mazda. The obstacles facing GM in its plans to close more auto factories became apparent on Tuesday as U.S. President Donald Trump threatened to block payment of government electric vehicle subsidies to GM. While it is not certain that Trump unilaterally has the power to do that, he made it clear he intends to use his office to pressure the company to keep open a small car plant in Ohio that GM says will stop building vehicles in March.

GM patent reveals new two-stage turbocharger

Modern turbochargers may be some of the best ever made, but performance is something that engineers are always trying to improve. According to GM Inside News, General Motors (GM) is hoping to alleviate some of the negative aspects of a two-stage turbocharger setup with a newly-patented design. The patent, that was filed on May 19, 2016, reveals a clever bypass system that allows the engine, a four-cylinder unit, to optimize both the low-pressure and high-pressure inlets for its respective functions. According to the filing, a conventional two-stage turbocharger setup is engineered to allow both turbines to operate simultaneously at low and mid engine speeds. At high engine speeds, only the low-pressure turbine works. The setup can't isolate either the low or high pressure side, which can impair low-end performance. GM's new two-stage turbocharger setup looks to eliminate this by linking the high-pressure turbo to the exhaust manifold through the high-pressure inlet duct. The low-pressure turbo is attached to the high-pressure turbo by a low-pressure inlet duct, which is linked to a connecting channel. A single actuator that is housed in the exhaust manifold creates a bypass that can opens the high-pressure inlet or close the connecting channel. Depending on what the engine load and speed is, the ECU guides the actuator—a single rotating spindle with discs corresponding to flanges on the high and low pressure sides—to isolate one of the two turbos. Isolating the turbos allow the respective inlets to be engineered for the best possible fluid dynamic performance. The setup should increase performance and decrease lag. There's no word on what car this setup will make an appearance on, but it will most likely be used in premium vehicles before trickling down to the rest of GM's vehicles. Related Video: News Source: GM Inside News, AutoGuide via GM Authority Cadillac Chevrolet GM Technology Sedan turbo patent engine turbocharging

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.