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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.

Weekly Recap: Autonomous driving goes commercial in Nevada

Nevada granted Daimler Trucks North America the first license to run an autonomous commercial vehicle on public roads in the United States Tuesday, marking another milestone in the technology's rapid advancement. Gov. Brian Sandoval and Daimler truck chief Wolfgang Bernhard promptly used the license to lap Highway 15 near Las Vegas in a newly revealed Freightliner Inspiration Truck. It was a clear signal that autonomous driving is big-rig reality, though it's still a long way from widespread use. Nevada certified two of Daimler's Freightliner Inspiration Trucks, which use the company's Highway Pilot system with a stereo camera, radar, and lane-keeping collision-prevention features to regulate the brakes and steering. The radar component has a long-range sensor that can cover 820 feet at an 18-degree angle and a shorter-range unit that stretches 230 feet at a 130-degree angle. The Inspiration trucks are based on the existing Freightliner Cascadia Evolution model used on US roads. In addition to the autonomous technologies, it also has futuristic design cues, including blue lighting in the front and a new hood and grille. While there are only two Freightliner Inspiration trucks in existence, Daimler expects to bring the Highway Pilot system into mass-produced big rigs by 2025, in time to capitalize on the market's predicted growth. The German truckmaker predicts the global hauling market will triple by 2050, and the United States will be a key part of that growth. Trucks carry 69.1 percent the nation's domestic freight tonnage and hauled 9.7 billion tons of freight in 2013, according to the American Trucking Association. Daimler expects autonomous driving to augment this growth, and perhaps evolve the role of the truck driver. Still, the company points out autonomous tech is not meant to replace drivers, but to assist them and relieve fatigue and monotony on long hauls. The driver has to stay in control for passing, in city traffic, and when hooking up the trailer. The company said autonomous driving also offers the potential for improved fuel economy – tests showed a five-percent gain – and lower maintenance costs. Daimler also said the technology could reduce congestion on the road. Much of this is attributable to the constant flow of traffic, which is aided by autonomous driving. While the benefits are becoming increasingly apparent, autonomous technology is still met with skepticism.

GM won't really kill off the Chevy Volt and Cadillac CT6, will it?

General Motors is apparently considering killing off six slow-selling models by 2020, according to Reuters. But is that really likely? The news is mentioned in a story where UAW president Dennis Williams notes that slumping US car sales could threaten jobs at low-volume factories. Still, we're skeptical that GM is really serious about killing those cars. Reuters specifically calls out the Buick LaCrosse, Cadillac CT6, Cadillac XTS, Chevrolet Impala, Chevrolet Sonic, and the Chevrolet Volt. Most of these have been redesigned or refreshed within the past few model years. Four - the LaCrosse, Impala, CT6, and Volt - are built in the Hamtramck factory in Detroit. That plant has made only 35,000 cars this year - down 32 percent from 2016. A typical GM plant builds 200,000-300,000 vehicles a year. Of all the cars Williams listed, killing the XTS, Impala, and Sonic make the most sense. They're older and don't sell particularly well. On the other hand, axing the other three seems like an odd move. It would leave Buick and Cadillac without flagship sedans, at least until the rumored Cadillac CT8 arrives. The CT6 was a big investment for GM and backing out after just a few years would be a huge loss. It also uses GM's latest and best materials and technology, making us even more skeptical. The Volt is a hugely important car for Chevrolet, and supplementing it with a crossover makes more sense than replacing it with one. Offering one model with a range of powertrain variants like the Hyundai Ioniq and Toyota Prius might be another route GM could take. All six of these vehicles are sedans, Yes, crossover sales are booming, but there's still a huge market for cars. Backing away from these would be essentially giving up sales to competitors from around the globe. The UAW might simply be publicly pushing GM to move crossover production to Hamtramck to avoid closing the plant and laying off workers. Sales of passenger cars are down across both GM and the industry. Consolidating production in other plants and closing Hamtramck rather than having a single facility focus on sedans might make more sense from a business perspective. GM is also trying to reduce its unsold inventory, meaning current production may be slowed or halted while current cars move into customer hands. There's a lot of politics that goes into building a car. GM wants to do what makes the most sense from a business perspective, while the UAW doesn't workers to lose their jobs when a factory closes.