Why did people spec auto on performance cars?

[Olivera]

xjay1337 said:

Ooof. 30kph over read and a 100-200 time of nearly 10 seconds! My m135i with a remap would be quicker

It took me about 0.1 seconds to release the timing on the right is completely wrong. Unless you are suggesting it really does 0-60 in 9.83s and 1/4 mile in 17.39s?

[xjay1337]

Olivera said:

xjay1337 said:

Ooof. 30kph over read and a 100-200 time of nearly 10 seconds! My m135i with a remap would be quicker

It took me about 0.1 seconds to release the timing on the right is completely wrong. Unless you are suggesting it really does 0-60 in 9.83s and 1/4 mile in 17.39s?

It's not wrong at all.

Have you ever used Dragy? Because I have.

The reason the 1/4 mile and 0-60 time are because you can see the car at 40 seconds has already driven 12.5m I suspect it was allowed to roll slightly, then it accelerated very slightly and then coated briefly. Proper acceleration doesn't start until 43 seconds which is presumably a good 6 or 7 seconds prior to the start of the run.

The speed on the Dragy app matches the gearchanges and change in throttle (IE when let off at the end of the run)
So yes that car on that road did 100-200 in nearly 10 seconds.

[Olivera]

xjay1337 said:

It's not wrong at all.

Have you ever used Dragy? Because I have.

I've little interest in Dragy, as it tends to be PDK/DSG timing obsessives that are into it.

Anyway, later in the video he gets 8.29 seconds for the exact same 100-200 run as before. Sorry but I'm not going to trust any timing with that much of a discrepancy between runs.

[bcr5784]

otolith said:

I think if that makes any difference, you are cutting your overtakes too close.

That second means I can leave a second more margin if I choose - either way it's significant. Actually if mid overtake I have to make an upshift then that's another second in my pocket with DCT. Given that an overtake at modest speeds probably only takes say 5 seconds (that's about the 40-80mph time for something like a PDK Cayman) 1 or 2 seconds is significant.

[bcr5784]

av185 said:

A second to change gear manually?

If so you need tuition.

Believe me it makes no difference whatsoever in the same car manual v flappy paddle on the road and overtaking opportunities.

I have a 991.2 GT3 manual and have owned the same car but PDK S which is one of the quickest and best man autos in fact betters the Ferrari 458 and 488 imo.

The other aspect is that the performance on many autos is blunted compared to manual due to more weight and also parasitic losses of the auto box.

See
https://en.wikipedia.org/wiki/Shift_time you will see that it quotes a time of 1-2 seconds for a cross gate shift (ie the time you are off the gas)

[RobM77]

av185 said:

bcr5784 said:

av185 said:

For road use there really is no difference in rapidity between a manual and flappy paddle.

Really makes no difference whatsoever on overtaking opportunities either.

It will take a second (at very least - probably more) to do an across gate shift from 3rd to second in a manual box. So unless you permanently go around in second on the offchance that an overtaking opportunity will arise there will doubtless be (and are) occasions when a good auto will allow you to overtake safely where you couldn't with a manual simply because you have an extra second to play with.

A second to change gear manually?

If so you need tuition.

Believe me it makes no difference whatsoever in the same car manual v flappy paddle on the road and overtaking opportunities.

I have a 991.2 GT3 manual and have owned the same car but PDK S which is one of the quickest and best man autos in fact betters the Ferrari 458 and 488 imo.

The other aspect is that the performance on many autos is blunted compared to manual due to more weight and also parasitic losses of the auto box.

I understand and agree with the spirit of what you're saying; manual boxes are lighter and they're far more engaging to use for most keen drivers. Timing is banned on most track days and effectively illegal on the road, so the merits of a manual box apply perfectly to a road going sports car that's intended to be entertaining to drive (911 GT3, Elise, Caterham etc). However, in terms of gearchange speed, what you're saying is not correct. One of the most common auto boxes these days is the ZF8, which can shift in as little as 200ms (a separate 'sport' mode in most applications, like my 530d for example). If we ignore clutchless shifts using racing dog ring gearboxes, there's no way that a normal driver using the clutch with an H pattern gearbox could replicate that sort of speed.

https://en.wikipedia.org/wiki/Shift_time (there's no citation, but this page quotes about 0.5s for a fast manual shift)

https://en.wikipedia.org/wiki/ZF_8HP_transmission (200ms)

You can see the above realised in quoted 0-60 times of cars that come with a manual gearbox and an auto. In some rare instances a car is quicker with a manual gearbox (like the M2 Competition: https://www.bmwblog.com/2019/07/18/is-the-bmw-m2-c... but this is rare and usually the auto is faster, purely due to the shift time, which is worth more than the small losses due to the car weighing more.

[bcr5784]

https://en.wikipedia.org/wiki/Shift_time (there's no citation, but this page quotes about 0.5s for a fast manual shift)

https://en.wikipedia.org/wiki/ZF_8HP_transmission (200ms)

[/quote]

The 0.5-1 second figure is for an in plane shift - I was specifically talking a cross gate shift which is far more common at road speeds certainly with the Porsches you mention.

[J4CKO]

xjay1337 said:

maz8062 said:

For me, this is the best sounding auto box that I've heard in a while:

https://www.youtube.com/watch?v=BNpZeZBaiZ0

I think it's a single-clutch auto

Ooof. 30kph over read and a 100-200 time of nearly 10 seconds! My m135i with a remap would be quicker

This though .... : https://www.youtube.com/watch?v=YppGvdSV7Hg

That is what has got silly, I have mine slightly tuned with a box, and its not even up there these days with the faster stuff, was going to go M4 next but I think I would just lose my license, so will go for a Mini JCW or something. Opting out of the BHP escalation.

Our Fiesta ST is way more fun than the M135i.

[Olivera]

Here's pro-driver results of same car, same track, but manual vs PDK:



Negligible difference.

[smartie93]

Olivera said:

Here's pro-driver results of same car, same track, but manual vs PDK:



Negligible difference.

What are you doing? You're going to hurt some feelings and egos with a factual evidence based post like that

[otolith]

bcr5784 said:

otolith said:

I think if that makes any difference, you are cutting your overtakes too close.

That second means I can leave a second more margin if I choose - either way it's significant. Actually if mid overtake I have to make an upshift then that's another second in my pocket with DCT. Given that an overtake at modest speeds probably only takes say 5 seconds (that's about the 40-80mph time for something like a PDK Cayman) 1 or 2 seconds is significant.

I guess it depends on your driving style, but I would spend more time assessing and planning an overtake than it takes to change gear in a manual or automatic car. If it isn't still on after a gear change, it wasn't ever on in the first place.

[Uncle boshy]

Depends on the car as well.

I used to have an auto bmw f11, in sport mode it was great, the gearbox using gps input to ensure it was always in the right gear at roundabouts etc. I did test a manual f11 and it wasn’t as good, not a particularly good manual.

In my mgf the manual is far superior to the slush box.

I’ve now got an egolf, ( only 1 gear) and the instant power take up is quite addictive on a winding road

[RobM77]

Olivera said:

Here's pro-driver results of same car, same track, but manual vs PDK:



Negligible difference.

Ah.. we need to be careful here how we're defining 'faster'. There are three types of fast:

• Acceleration in a straight line. A manual car is typically lighter, and F=ma, but manual gearchanges usually take longer than PDK or auto gearchanges (see above). Additionally, there can be differences pulling away from rest with how clutch slip is managed, so we can divide this area into acceleration from rest and acceleration when already rolling. The end result of all of these contributing factors in the real world is that usually autos are faster, but there are exceptions (see link above for the M2C).

• Around a track. All the above factors apply, but weight also counts against a car in braking and cornering as well as acceleration, so a manual car has more going for it. It's still a balance though, depending on the track, the car etc.

• Top speed. Weight is irrelevant, it's just down to drivetrain losses. I think modern auto boxes lock the torque converter when in gear, so there shouldn't be a difference? (I'm awaiting someone who knows more to fill in the gaps there).

[ITP]

maz8062 said:

DoubleD said:

bcr5784 said:

Olivera said:

The 'autos are faster' is a nonsense argument for road driving. A few 100ms faster here or there makes next to no difference, what does make a difference to all-out performance is just how reckless and stupid the driver is with regards to keeping their foot-in [on the accelerator].

Well actually is does make a significant difference. It means you can change gear when it would be impossible because of time constraints or simply because you are in a corner and to change gear manually would unsettle the car - which doesn't happen with a smooth auto because there is no interruption in power.

I presume that you are talking about driving on a track? It certainly doesn't make a significant difference on the road.

It makes a huge difference. I have an old-style 7g gearbox in my Merc. I can approach a roundabout in top gear, pull and hold the downshift paddle and the box will find the most accelerative gear to use through the roundabout. Yes, this can be done in a manual but it is much harder to gauge what would be the best gear - 2nd/3rd? This can all be done without letting go of that spherical object that we like holding on to

Harder to gauge what gear you need in a manual?
I tend to use my eyes. It’s easy.

I think you’ll find the gearbox in your merc can’t actually see every individual roundabout and all the traffic around it and all it is doing is giving you the lowest gear available for a set speed if you pull and hold the paddle. It would do this if it was approaching a t-junction, or you’re own driveway if you approach your house at speed, brake late and hold the paddle. It will then select the correct gear to accelerate up your driveway.

Edited by ITP on Thursday 25th June 18:13

[bcr5784]

I think Porsche's own acceleration figures are pretty factual and corroborated by any number of road tests.

[DoubleD]

We are all trying to blind each other with science.

Which ever you prefer is the best gearbox for you.

[xjay1337]

Olivera said:

xjay1337 said:

It's not wrong at all.

Have you ever used Dragy? Because I have.

I've little interest in Dragy, as it tends to be PDK/DSG timing obsessives that are into it.

Anyway, later in the video he gets 8.29 seconds for the exact same 100-200 run as before. Sorry but I'm not going to trust any timing with that much of a discrepancy between runs.

It's OK to admit you are wrong.

The timing gear is reasonably accurate. Dragy is widely accepted to be a suitable way of comparing performance of vehicles. , it's a 10hz dedicated GPS device so accurate to within around 0.1 second which is plenty enough for

You know cars can perform slightly differently on different runs... things like changing a few hundred RPM earlier or later can make a big difference to a run time..............so can things like small differences in incline.

Just because YOU don't trust it doesn't take anything away from the fact this particular Murcielago was not only slow but had an incredibly ambitious speedo.

[anonymous-user]

What's real rubbish isn't manual and it isn't auto - it's driving a multi-gear auto on the paddles. The idea that a human driver can asses gearchange points better than the computer is fanciful. The auto will work through many more shifts and much more quickly than a human. The real use for paddles is an occasional downshift to prepare for an event the transmission can't see coming, such as an overtake. Beyond that it's best to leave the gearbox to do its own thing.

Regarding 0-60 times and lap times for manual cars it's worth remembering the high levels of mechanical abuse that are required to achieve them, whereas an auto just does the standing starts and puts in the laps while quietly minding its own business.

[xjay1337]

J4CKO said:

Our Fiesta ST is way more fun than the M135i.

I can imagine, but for me on track I will never go back to a FWD.

On the road then it's probably more fun sure, but on track, no way.

[av185]

RobM77 said:

av185 said:

bcr5784 said:

av185 said:

For road use there really is no difference in rapidity between a manual and flappy paddle.

Really makes no difference whatsoever on overtaking opportunities either.

It will take a second (at very least - probably more) to do an across gate shift from 3rd to second in a manual box. So unless you permanently go around in second on the offchance that an overtaking opportunity will arise there will doubtless be (and are) occasions when a good auto will allow you to overtake safely where you couldn't with a manual simply because you have an extra second to play with.

A second to change gear manually?

If so you need tuition.

Believe me it makes no difference whatsoever in the same car manual v flappy paddle on the road and overtaking opportunities.

I have a 991.2 GT3 manual and have owned the same car but PDK S which is one of the quickest and best man autos in fact betters the Ferrari 458 and 488 imo.

The other aspect is that the performance on many autos is blunted compared to manual due to more weight and also parasitic losses of the auto box.

I understand and agree with the spirit of what you're saying; manual boxes are lighter and they're far more engaging to use for most keen drivers. Timing is banned on most track days and effectively illegal on the road, so the merits of a manual box apply perfectly to a road going sports car that's intended to be entertaining to drive (911 GT3, Elise, Caterham etc). However, in terms of gearchange speed, what you're saying is not correct. One of the most common auto boxes these days is the ZF8, which can shift in as little as 200ms (a separate 'sport' mode in most applications, like my 530d for example). If we ignore clutchless shifts using racing dog ring gearboxes, there's no way that a normal driver using the clutch with an H pattern gearbox could replicate that sort of speed.

https://en.wikipedia.org/wiki/Shift_time (there's no citation, but this page quotes about 0.5s for a fast manual shift)

https://en.wikipedia.org/wiki/ZF_8HP_transmission (200ms)

You can see the above realised in quoted 0-60 times of cars that come with a manual gearbox and an auto. In some rare instances a car is quicker with a manual gearbox (like the M2 Competition: https://www.bmwblog.com/2019/07/18/is-the-bmw-m2-c... but this is rare and usually the auto is faster, purely due to the shift time, which is worth more than the small losses due to the car weighing more.

Interesting points.

As previously mentioned the latest 991.2 GT3 manual has a flatshift option on the upshifts allowing much faster upchanges due to there being no need to adjust the revs and by keeping your foot pinned on the accelerator.

The other aspect to this of course is how fast do we want our auto manual gearchanges to actually be. If you contrast the e46 m3 archaic single clutch smg gearbox with the latest dct or PDK S wet double clutch gearboxes from Porsche there is of course no comparison although the smg somewhat suits the e46 performance wise. Also how bizarre is it that an Aventador approaching £300k still retains its single clutch gearbox which really provides little more than the aged smg box but somehow produces the idiosyncratic elements to the already quirky Lambo that buyers want.

Imo it is a balance between rapid enough changes and character and I for one would shun any vehicle which had seamless gearchanges although this is doubtless where vehicles are heading with full autonomy where driver interaction will ultimately be history and the world a much sadder place.