is it true automatics accelerate slower than manuals ?

[maverickdrives]

The initial message was deleted from this topic on 29 December 2020 at 20:20

[creampuff]

Torque converters increase torque. But lose power.

[Fattyfat]

On a like for like basis engine wise, I'd say so.

[LeoSayer]

The Porsche 997 turbo torque converter auto has a quicker official 0-60 time than the manual.

It's a rare exception to the rule.

[creampuff]

maverickdrives said:

I dont get that, so you will get more torque and less power out of an automatic?

A torque converter is like another, continuously variable, gearbox. It does multiply torque but it is not 100pc efficient in transmitting power.

[williamp]

certainly in the olden days (fields as far as the eye could see etc) when you could have a car (lets say an Aston V8, XJS etc) with either a 5 speed manual or a 3 speed auto. So you had lost two gears even before you have the converter to sap power.

You could specify a different rear axle ratio to suit, but then you would sacrifice top speed/ mpg for better acceleration.

[creampuff]

http://en.wikipedia.org/wiki/Torque_converter#Effi...

[vikingaero]

If you have two identical models, one manual and one auto, then generally the manual will be faster.

I inherited my Mums Corsa B 1.4 auto and it was faster than any car away from the traffic lights - BMW's, Mercs etc .... up to about 30mph, when I would be wasted.

[creampuff]

williamp said:

certainly in the olden days (fields as far as the eye could see etc) when you could have a car (lets say an Aston V8, XJS etc) with either a 5 speed manual or a 3 speed auto. So you had lost two gears even before you have the converter to sap power.

You could specify a different rear axle ratio to suit, but then you would sacrifice top speed/ mpg for better acceleration.

You could also get some Yank Tanks or big Australian cars with 2-speed automatics!

[NNH]

Traditional automatics have:
- torque converters that are less efficient at transmitting power than a clutch
- more weight than a manual gearbox
- fewer ratios than a manual, so a less optimal gearing at most times during acceleration.

All these factors made an automatic quite a bit slower (in acceleration and top speed) than a manual. More modern automatics have locking torque converters in some gears, are lighter than they were, and have lots of ratios.

The Porsche 997T example was because its torque converter would allow the engine to rev up to maximum torque with the turbos at full flow before launch. This gave a better 0-60 figure than the manual which had to contend with turbo lag off the line. However, the manual's performance above 60mph was better, with a better 0-125 time and a higher top speed.

[r129sl]

The difference is generally pretty marginal and, for most of us, in reality, imperfect clutch control and gear changing are likely to see the manual car slower than the automatic. Or maybe it is just me who is not a driving god.

[eldar]

creampuff said:

You could also get some Yank Tanks or big Australian cars with 2-speed automatics!

And UK cars with 3 speed manuals - notably the Vauxhall FC Series Victor & VX4/90. 4 speed was an option with posh seats.

[creampuff]

eldar said:

And UK cars with 3 speed manuals - notably the Vauxhall FC Series Victor & VX4/90. 4 speed was an option with posh seats.

I drove a current model Ford Falcon ute with a 3-speed column shift in Australia not that many years ago.

[Markgenesis]

vikingaero said:

I inherited my Mums Corsa B 1.4 auto and it was faster than any car away from the traffic lights - BMW's, Mercs etc .... up to about 30mph, when I would be wasted.

Are you serious ?

Also has anyone mentioned manually shifting an auto ?, this can even be done in old Yank muscle cars, did it all the time in my 70 Mach 1 (under full throttle), regularly took the engine to 5K each shift.

Also burn out with an auto = 1st gear (or "D") left foot on brake, throttle motor to 2.5/3K, footbrake off and floor it.

Nothing wrong with an auto, just needs a good driver.

[copperman05]

I would say the older generation of autos were slower yes but the latest generation such as the ZF8 found in the m135i are faster than their manual counterparts.
Slush boxes have come a long way in the past few years the latest gen are almost hybrid, still using torque converters but performing similar to a DSG.

[David87]

The really modern automatics are superior to manuals in terms of both speed and economy - take the M135i 6-speed manual vs. the ZF 8-speed automatic:

Combined MPG
M: 35.3
A: 37.7

CO2 Emissions (g/km)
M: 188.0
A: 175.0

0-62mph (secs)
M: 5.1
A: 4.9

[tagy]

vikingaero said:

I inherited my Mums Corsa B 1.4 auto and it was faster than any car away from the traffic lights - BMW's, Mercs etc .... up to about 30mph, when I would be wasted.

[anonymous-user]

vikingaero said:

I inherited my Mums Corsa B 1.4 auto and it was faster than any car away from the traffic lights - BMW's, Mercs etc .... up to about 30mph, when I would be wasted.

I'm still convinced that the 1.4 Fiat Panda courtesy car that I get from the local garage has the quickest 0-20 time of any car on the road. No matter what the situation, you will be the quickest car off the lights every single time, with no effort at all. It's actually quite staggering.

Of course, beyond 20mph you get obliterated by LDV Convoy minibuses.

[cologne2792]

I remember the last wedge shape 3.0 Supra being tested, admittedly a very long time ago.
The manual and auto were pitted against each other with the same driver.
Manual 0-60 was 6.6 seconds and the auto 7.5.
Difference was that the manual time was the best achieved with a balance of wheel spin, revs and lots of noise whereas the auto managed it's time consistently and painlessly.

[Vladimir]

I drove a VW Up loan car today. The worst auto gearbox I have ever used; I genuinely thought it was broken. I reckon almost two seconds between shifts and big lurch each time.
Makes our M135i auto seem very sophisticated!