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This map reveals the cleanest vehicles based on location

Naysayers love to point out how dirty the electricity grid mix is when it comes to charging electric vehicles. Curmudgeons are eager to jump into any conversation about EVs to enlighten the lucky listeners about how plug-in cars contribute to pollution, sometimes even throwing in a dash of climate-change denial for good measure. (Thanks, buddy. Pray, tell me more about the plight of oppressed SUV owners.) Unless someone buys an EV just because they think they're cool (which, yeah, they often are), they probably have at least a passable understanding of their environmental pros and cons. As many EV owners are already aware, location has a lot to do with any particular plug-in car's carbon footprint. Still, there's always more to know, and knowledge is not a bad thing, especially if one uses it to do the right thing. That's why this handy-dandy map from Carnegie Mellon University is so interesting. CMU researchers have compiled information about the lifecycle greenhouse gas emissions of various EVs based on where they're charged, as compared to gasoline-powered vehicles. The researchers looked at the Nissan Leaf, Chevrolet Volt, and Prius Plug-In Hybrid versus the gasoline-dependent Toyota Prius hybrid and the stop-start-equipped Mazda3 with i-ELOOP and compared grams of CO2 emitted per mile. CMU takes into account the grid mix, ambient temperature, and driving patterns. CMU takes into account the grid mix based on county, as well as ambient temperature and driving patterns in terms of miles traveled on the highway or in the city. For instance, if you drive a Nissan Leaf in urban areas of California, Texas, or Florida, your carbon footprint is lower than it would be if you were driving a standard Toyota Prius. However, if you charge your Leaf in the Midwest or the South, for the most part, you've got a larger carbon footprint than the Prius. If you live in the rural Midwest, you'd probably even be better off driving a Mazda3. Throughout the country, the Chevrolet Volt has a larger carbon footprint than the Toyota Prius, but a smaller one than the Mazda3 in a lot of urban counties in the US. The Prius and Prius Plug-In are relatively equal across the US. Having trouble keeping it straight? That's not surprising. The comparisons between plug-in and gasoline vehicles are much more nuanced than the loudest voices usually let on.

'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).

Frustrated GM investors ask what more Mary Barra can do

DETROIT — General Motors Co Chief Executive Mary Barra has transformed the No. 1 U.S. automaker in her almost five years in charge, but that is still not enough to satisfy investors. Ahead of third-quarter results due on Oct. 31, GM shares are trading about 6 percent below the $33 per share price at which they launched in 2010 in a post-bankruptcy initial public offering. The Detroit carmaker's stock is down 22 percent since Barra took over in January 2014. After hitting an all-time high of $46.48 on Oct. 24, 2017, the shares have declined 33 percent. In the same period, the Standard & Poor's 500 index has climbed 7.8 percent. Several shareholders contacted by Reuters said GM could face a third major action by activist shareholders in less than four years if the share price does not improve. "I've been expecting it," said John Levin, chairman of Levin Capital Strategies. "It just seems a tempting morsel to somebody." Levin's firm owns more than seven million GM shares. Barra has guided the company through the settlement of a federal criminal probe of a mishandled safety recall, sold off money-losing European operations, and returned $25 billion to shareholders through dividends and stock buybacks from 2012 through 2017. GM declined to comment for this story, but the company's executives privately express frustration with the market's reluctance to see it as anything more than a manufacturer tied mainly to auto market sales cycles. GM's profitable North American truck and SUV business and its money-making China operations are valued at just $14 billion, excluding the value of GM's stake in its $14.6 billion Cruise automated vehicle business and its cash reserves from its $44 billion market capitalization. The recent slump in the Chinese market, GM's largest, and plateauing U.S. demand are ratcheting up the pressure. GM is one of the few global automakers without a founding family or a government to serve as a bulwark against corporate raiders. In 2015, a group led by investor Harry Wilson pressed GM to launch a $5 billion share buyback, and commit to what is now an $18 billion ceiling on the level of cash the company would hold. In 2017, GM fended off a call by hedge fund manager David Einhorn to split its common stock shares into two classes. Einhorn, whose firm still owned more than 21 million shares at the end of June, declined to comment about GM's stock price. Other investors said there were no clear alternatives to Barra's approach.