1985/5 944 Porsche on 2040-cars

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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.

40+ cars that barely avoid the gas guzzler tax

The Gas Guzzler schedule, with mpg ratings and charges that haven't changed since 1991, lays out which fuel-swillers owe what to Uncle Sam.
I started thinking about the "Gas Guzzler Tax" - considerably less well known as The Energy Tax Act of 1978 - when I was driving Dodge's new Challenger SRT Hellcat last week. Unsurprisingly for a car that can burn 1.5 gallons of gas per minute at max tilt, theoretically able to empty a full tank of premium in about 13 minutes, the Hellcat will be subject to the Gas Guzzler Tax schedule when it goes on sale.

Here's how to follow this weekend's 24 Hours of Le Mans

In the pantheon of motorsports, the 24 Hours of Le Mans stands as one of the great endurance challenges to man and machine. This year's event in France already looks to be one for the ages with Porsche setting record-breaking times in practice and the competition debut of Nissan's front-engine, hybrid racer. Thankfully, there's a massive list of ways to follow this automotive attraction. Reilly Brennan, the Executive Director of the Revs Automotive Research Program at Stanford University, and a friend of Autoblog, has once again assembled a helpful couch-kit to organize many of the options. Unfortunately, the old-school way of just turning on the television might be the most frustrating way to watch Le Mans this year. Fox Sports 1 and 2 are carrying about half the race, but the coverage bounces between them seemingly at random. The broadcast begins on Fox Sports 2 at 8:30 AM Eastern ahead of the 9:00 AM start and lasts there until 12:00 PM. Things don't pick up again until 7:00 PM Eastern on Fox Sports 1 for an hour, and the channels swap back and forth more from there. The Fox Sports Go streaming app offers more, but even it stops showing the race a few times. Thankfully, streaming Le Mans is easy. If you can't dedicate 24-hours on the couch, Radio Le Mans lets you listen to audio commentary anywhere with some of the best announcers in the biz. The Automobile Club de l'Ouest, the governing body for the race, also offers an official video stream in an app for $9.99. For a really low-tech solution, the official Twitter is another choice. Brennan is keeping his list updated with coverage changes. You can also check out and download the spotter's guide (from Nissan) in the gallery above. Enjoy this year's race. If you miss anything, don't worry; expect a full report from Autoblog. In fact, editor-in-chief Mike Austin is attending Le Mans this year, so follow him on Twitter for on-the-fly impressions. Featured Gallery 2015 24 Hours of Le Mans Spotter's Guide News Source: Reilly BrennanImage Credit: Nissan Motorsports Audi Nissan Porsche Toyota Hybrid Racing Vehicles