I know that a TCU automates the operation of the clutch. But I'm clueless on how an AMT can do anything a human does using a manual.

1)If you are stopped at a hill. When pulling off, a driver brings clutch to biting point so that the car wont roll back. If an AMT does it, how will it know when and how long to hold a half clutch. Wont it burn the clutch compared to a human?

2) In slow moving traffic, a manual driver creeps along by regulating the clutch depression.

3) Manual drivers use clutch while approaching a junction or roundabout to freely coast thus saving fuel compared to continuous downshifting.

How can an AMT be intelligent enough? Wont it destroy the clutch? Why is it gaining popularity recently in cars?

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    Point 3 is incorrect - leaving the transmission in gear saves more gas than neutral.
    – Bob Cross
    Commented May 8, 2014 at 13:36
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    @BobCross ... I think I would disagree with that statment. Commented May 8, 2014 at 15:15
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    After reading this article, I'm wondering if Magneti Marelli is even allowing the specifics of how it works out into the market place. Commented May 8, 2014 at 15:43
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    @Paulster2, overall and instantaneous fuel consumption are measurable at all times on modern cars. It's an easy experiment to do so there's no need for debate - you can find out the answer quickly.
    – Bob Cross
    Commented May 8, 2014 at 16:35
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    @JuannStrauss, when you are decelerating (or coasting), the gearbox is being turned by the roadwheels, and if you leave it in gear, it then turns the engine - the ECU knows this and cuts the fuelling right down to the bare minimum (or off completely), and lets momentum do the work for it - whereas if you disengage the clutch, the ECU needs to provide enough fuel to keep the engine turning. It is the same principle as the regenerative braking used in modern Hybrids...
    – Nick C
    Commented May 9, 2014 at 9:06

1 Answer 1


An AMT does the same things an automatic gearbox does, though with a bit more intelligence and in a markedly different way.

I don't know how they were engineered, but if I were doing the software, I'd consider engine RPM, load, vehicle speed, current gear, required gear and maybe some historical driving data (if I wanted to get fancy) to decide how fast to modulate the clutch. If you're at 7000RPM going 100MPH in 4th gear, I'd give you instantaneous clutch, but at 1800RPM in 1st gear, I'd take my sweet time.

  • Slow engagement/ disengagement in low gears makes sense actually. A friend who test drove one actually said so. He was however doubtful of how well it handles a clutch compared to a driver. Maybe we'll know that answer in 10yrs Commented May 9, 2014 at 16:04
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    Mitsubishi uses AMT systems in their Fuso range of commercial vehicles because they seem to require less servicing to the clutch and gearbox than manuals, so there's that. Commented May 9, 2014 at 18:18
  • Hmm. But dont trucks and city cars deal with very different situations? A city car would have to deal with a lot of half riding the clutch in heavy traffic. The condition may be worse in creeping at sloped junctions. A truck spends time on a freeway. What do you think? Commented May 11, 2014 at 8:50
  • Trucks cycle gears much more frequently than cars because they only rev to about 2000RPM. With that in mind, Mitsubishi seems to think an AMT is better at it than a human. It's not that big a leap to assume an AMT configured for city cars could do the same. Remember that this is F1 technology. Commented May 12, 2014 at 6:38
  • I would suggest Reading through this as it provides a nice viewpoint. team-bhp.com/forum/indian-car-scene/…
    – Shobin P
    Commented May 25, 2015 at 12:12

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