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Is the skill of rev matching being lost to computers?

If the ability to drive a vehicle equipped with a manual gearbox is becoming a lost art, then the skill of being able to match revs on downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. The usefulness of rev matching in street driving is limited most of the time – aside from sounding cool and impressing your friends. But out on a race track or the occasional fast, windy road, its benefits are abundantly clear. While in motion, the engine speed and wheel speed of a vehicle with a manual transmission are kept in sync when the clutch is engaged (i.e. when the clutch pedal is not being pressed down). However, when changing gear, that mechanical link is severed briefly, and the synchronization between the motor and wheels is broken. When upshifting during acceleration, this isn't much of an issue, as there's typically not a huge disparity between engine speed and wheel speed as a car accelerates. Rev-matching downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. But when slowing down and downshifting – as you might do when approaching a corner at a high rate of speed – that gap of time caused by the disengagement of the clutch from the engine causes the revs to drop. Without bringing up the revs somehow to help the engine speed match the wheel speed in the gear you're about to use, you'll typically get a sudden jolt when re-engaging the clutch as physics brings everything back into sync. That jolt can be a big problem when you're moving along swiftly, causing instability or even a loss of traction, particularly in rear-wheel-drive cars. So the point of rev matching is to blip the throttle simultaneously as you downshift gears in order to bring the engine speed to a closer match with the wheel speed before you re-engage the clutch in that lower gear, in turn providing a much smoother downshift. When braking is thrown in, you get heel-toe downshifting, which involves some dexterity to use all three pedals at the same time with just two feet – clutch in, slow the car while revving, clutch out. However, even if you're aware of heel-toe technique and the basic elements of how to perform a rev match, perfecting it to the point of making it useful can be difficult.

GM removes start/stop from full-size trucks and SUVs with V8 engines

GM is removing start/stop technology from a number of its popular full-size SUVs due to the ongoing chip shortage. This follows the removal of cylinder deactivation technology from some of its trucks, which was also due to the chip shortage. GM Authority first reported the news, but we’ve just confirmed everything with a GM spokesperson.  The following 2021 model year vehicles will be affected: Chevy Tahoe, Chevy Suburban, GMC Yukon, Cadillac Escalade, Chevrolet Silverado 1500 and GMC Sierra 1500. Only versions of those vehicles built with the 5.3-liter V8 or 6.2-liter V8 and mated to the 10-speed automatic will have the tech removed from them. Only vehicles manufactured on or after June 7 will be affected. “By taking this measure, it will enable us to continue production of our high-demand full-size SUV and pickups as the industry continues to rebound and strengthen,” GM said in a statement. Those who ultimately buy one of these vehicles without start/stop technology will receive a $50 discount off MSRP for their troubles. Losing this fuel-saving tech could be a big negative for some, but we know many folks turn it off anyway. Not having to press the button to deactivate start/stop every time could actually be a positive if youÂ’re part of the camp who does that already. 2021 Cadillac Escalade Sport Platinum View 27 Photos On the downside, GM says “most of the affected vehicles will experience a minor reduction in fuel economy.” We donÂ’t have revised window stickers in hand to know how each model will be affected, but any 1 mpg reduction will be rather impactful for vehicles rated as low as these trucks already are. Any reduction will be seen in the city mpg rating, so take the kind of driving youÂ’re going to be doing into account before purchasing. When it comes to greenhouse gas compliance rules, GM says it doesnÂ’t foresee this impacting the companyÂ’s average fleet score. It also intends to begin adding start/stop back to these models as soon as possible, but there will be no retrofit effort made to fit the tech to vehicles already built without it. “Our supply chain organization continues to make strides working with our supply base to mitigate the near-term impacts of the semiconductor situation,” GMÂ’s statement reads. “GM continues to leverage every available semiconductor to build and ship our most popular and in-demand products, including our highly profitable full-size trucks and SUVs for our customers.

These are the 'Greenest' and 'Meanest' cars in 2015

As has become tradition, the American Council for an Energy-Efficient Economy (ACEEE) has come up with a ranking of what it refers to as the "greenest" cars of 2015, and, by way of contrast, a list of the so-called "meanest" cars, so those who value eco-friendliness over all else can choose which vehicles they should or should not consider buying. As you may expect, electric cars make up the majority of the greenest cars on the list, but, perhaps surprisingly to many, the Tesla Model S didn't make the cut. It's worth noting, too, that where the electricity an owner uses to charge their electric vehicle has a big impact on its overall environmental impact. "A car that is charged using electricity generated from natural gas or renewables is going to have significantly less impact on the environment than one charged on a coal-heavy grid," says ACEEE lead vehicle analyst Shruti Vaidyanathan. The ACEEE's list for 2015 looks very different than it did in 2014. It's an interesting collection, though – and we're sure this goes without saying, really – we'd recommend doing a bit more research into each vehicle and how it might fit into your daily life before making any purchase decisions. Click here to see the ACEEE's list of the Greenest and Meanest vehicles sold in the United States in 2015. Green Bugatti Chevrolet Fiat GM GMC Mercedes-Benz Nissan RAM smart Toyota greenest greenest cars