Automatics less econmical than manuals?

ferry

Just curious.

Are automatics generally less economical than manuals?

If so why?

Like I day just curious!

Cheers
F x

macman

Yes, because auto transmission is generally less efficient than manual-and the transmission is usually heavier.

Gloomendoom

Conventional torque converter type automatic transmissions tend to be less efficient than manuals. How much less efficient does depend on the type of use though.

Modern automatics with one or two plate clutches instead of a torque converter can equal or better the economy of a manual gearbox.

reeac

ferry wrote: »

Just curious.

Are automatics generally less economical than manuals?

If so why?

Like I day just curious!

Cheers
F x

Early [especially American] auto gearboxes suffered from too few gears [2 or 3] and lots of slippage in the "fluid flywheel" e.g Buick Dynaslush [officially Dynaflow]. As the years went by they increased the number of gears and introduced the torque converter and slippage, which reduced as road speed increased,dropped to around 5% at 60 mph. Then mechanical lock-up on the highest ratio was introduced and I have a feeling that it's available on several ratios now. All of this means that conventional autos have become more efficient but cannot compete with manuals as regards fuel economy. The various CVT transmissions are in principle less lossy but personally I don't like those steel belts etc. Although CVT is often praised for enabling the engine to run at optimum speed for economy I doubt if that's a noticeable effect.

Iceweasel

The situation is now the complete reverse of what it was only ten years ago.

Auto-box technology has really moved on.

The latest automatic cars are not only more economical, but faster than the equivalent car with a manual gear-box.

Partly due to them having more gears - perhaps as many as 8 where the manual has 6.

gilbert_and_sullivan

Gloomendoom wrote: »

Modern automatics with one or two plate clutches instead of a torque converter can equal or better the economy of a manual gearbox.

Till they go wrong, then any possible fuel savings pale into insignificance when compared to the costs to put these things right.
An expensive risk to own one out of warranty.

Economy wise with these automanual boxes much depends on the driver, a point and steer merchant won't beat the computer, but a driver can and will.

Gloomendoom

gilbert_and_sullivan wrote: »

Till they go wrong, then any possible fuel savings pale into insignificance when compared to the costs to put these things right.

Not a problem if you have a warranty.

Mind you, my car has a slushbox. It's smoooooooth.

BTW the torque converter locks up in fourth and fifth.

attila_

Is there a car on autotrader which does higher mpg as auto than it does as manual? I can't find one.

colino

Slushpumps will always be slushpumps, unless you are overriding the auto gearbox for speed (why then do you want an auto?) they have a higher regard for passenger comfort than car transportation sense.
Autos will always, generally, be in the wrong gear, at the wrong time, than mr. gearjammer.

Rolandtheroadie

I'd previously tried towing with auto's and it was either rev the nuts off it in 2nd or have it in drive and it was jumping up and down.
The 2.5 auto I have just now, I'm sure its around 500rpm above our 2.5 manual at the same speed.
Both of these are in no way modern though.

Iceweasel

Here's my take on this - and I know that there are several folks who will disagree - but that's just life I suppose.

I was a late convert to auto-boxes having been put off by the terrible 3-speed autos that were available back in the 70s and 80s - even on so-called prestige marques such as M-Benz.

In those days I have to agree that folks who wanted an auto either couldn't handle a manual box well, or didn't care, or were fairly rich - or perhaps all of the above.

As an ex-rally driver (with some success) I considered that I could always do better at choosing and changing gears myself - so it came as a surprise a few years ago to discover that auto-boxes had very much moved on and were actually pretty good.

Not all of them of course - there are still some crappy examples - but generally speaking they are pretty good - certainly on anything with sporty pretentions.

I now doubt if I will ever buy a manual again - I have a 6-speed auto with steptronic manual possibilities to select the gears myself if I wish to.

However for 99% of the time I must admit that I leave the box in fully auto mode as I can't make better decisions that the electrickery that controls the box.

About the only time that I 'take control' personally is on steep hairpins bends while climbing Alpine passes - a holiday hobby to which I am addicted. LOL

I don't rely too much on published performance facts and figures but I believe an example of a car with an auto-box being faster and more economical would be the current BMW 3 series.

Compare the 320d auto with the manual version and I think the auto wins.

If not - there can't be much in it - and I would think in the real world, as opposed to Jeremy Clarksons type of world where every pedal becomes an on/off switch, the auto is the 'better' car.

Stand by for outraged responses.