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> Automatic is more fuel efficient I thought it was the opposite. Has that changed?

• randunel 4y ago
  It hasn't changed, automatic gearboxes still eat up more fuel than their manual counterparts on the same cars.
  • fjfaase 4y ago
    I think from a purely mechanical point of view, this is the case, meaning that if you have two cars, one with manual gearbox and one with an automatic gearbox, both driving at the same speed with the same gear ratio, the one with the automatic gearbox will likely use slightly more fuel. But even this might not the case at all possible speeds. But at some speeds when the car with the manual gearbox is using the wrong gear, it might use much more gas. The problem with the manual gearbox is not in the gearbox but the human using it. First of all, not all drivers know when is the best moment to change gears and even if they know, they are not always able to change gears at the right moment. When you are turning on a crossing and accelerating, switching gears can be difficult. Also automatic gearboxes can change gears usually much faster than humans. Operating the clutch is hard and when not done in the correct way, letting the clutch slip too much, waste energy. Taking this all into account, in many cases, an automatic transmission might be more efficient. I have been driving cars with manual transmissions all my life. My current car as indicator lights telling you when to change gears up and down. I often find myself skipping gears, especially when accelerating in the city, I often skip fourth gear. The car has six gears and you should already switch to the fifth gear when driving 50Km/h. My first car only had four gears, and the fourth gear was only used when driving over sixty. If a car has more gears it also means that you have to shift more often, which might make driving less efficient in city traffic due to the many more moments you shift slightly at the wrong moment.
    • randunel 4y ago
      The automatic gearbox frequently upshifts in error (for example, just before a hill, making a downshift immediate) and downshifts too late when overtaking, resulting in erratic behaviour, lots of revs, and considerably more fuel consumption. Taking this into account, in almost all cases cases, a manual transmission might be more efficient.
      • kllrnohj 4y ago
        None of what you describe costs fuel, nor does it cause "lots of revs"? Upshifting "too much" is the opposite, it's fewer revs (and therefore less fuel used, not more)
• fragmede 4y ago
  Yes. Technology advanced and CVTs and 10-speed dual-clutch automatic transmissions are now more (by 1-2 mpg) more efficient than manual transmissions.
  • masklinn 4y ago
    I’ve been told even the old torque converter style has been upgraded with direct coupling, so you get fluid coupling (and its smoothness) while shifting, and direct coupling (and its efficiency) once in gear.
  • randunel 4y ago
    I doubt it's changed under real driving conditions, with hills, valleys and overtaking happening frequently, where all types of automatic transmissions perform poorly (they can't possibly anticipate an oncoming hill or overtaking, whereas the driver manually shifts to the correct gear beforehand).
    • masklinn 4y ago
      Every automatic car I’ve driven would e.g. quickly downshift when pressing down the accelerator, and while this can be laggy with older AMTs I’d assume it’s not an issue on modern gearboxes, at least the not-super-cheapo ones. But probably more relevant, all automatics I’ve driven have “manual” shifters (paddles or +/- selector on the gear lever) which let you override the gearbox’s decisions, to an extent. So nothing precludes anticipating your gearing, even on an automatic.
    • kllrnohj 4y ago
      What you're talking about makes a manual have fewer torque brownouts for lack of a better term, but they'd cost efficiency not gain it. Being in a lower gear before you need it is worse for mpg than being in it slightly "too late"