[L99BEN]

Not really much data on the following after searching.
The auto has proven to be quicker from a dig but how about from a roll stock vs stock?
e.g. 40-120 roll race.

Does the auto actually pull as hard as the manual in-gear or is the advantage mainly in the faster shifts?

A8 advantage:

Faster shifts
Transmission has more aggressive gearing

6M advantage:

More power to the wheels (not sure how much actually)
a little lighter (around 60 lbs)
longer gears allowing you to stay in powerband longer in the lower gears.

I test drove both. Other than longer gears in the 6M, they felt similar in a straight line (sotp) in gear to me.
and yes we all know the manual is more fun.

[Richard0nee]

From a dig Auto has the advantage.. from a roll my money is on the M6. There is a video of this and the M6 won by a car I believe. It's on YouTube.

[L99BEN]

Originally Posted by Richard0nee

From a dig Auto has the advantage.. from a roll my money is on the M6. There is a video of this and the M6 won by a car I believe. It's on YouTube.

I just saw that video. One little roll race on you tube isn't enough evidence for a clear conclusion imo.

[hotlap]

The A8 has a significant gearing advantage in its first three gears so it has the edge to ~90 mph. They aren't far apart in the later gears. The A8 will shift faster throughout.

[SuperSound]

Yea not seeing how the M6 will have any advantage in a roll. Some people think the delay on downshift (in auto) is why the M6 has an advantage, but you can hold a gear in the A8 too. So there is no delay if this is a planned race. Now if you want to be the ricer who suddenly smashes the pedal, then yea the M6 will have an advantage for a sec.

[Ian SS]

With a good driver, slight advantage to the M6.

[travislambert]

The manual has a little less power loss through the transmission which mostly offsets the gearing advantage of the automatic. However, the automatic will still usually edge out a manual.

[L99BEN]

Originally Posted by travislambert

The manual has a little less power loss through the transmission which mostly offsets the gearing advantage of the automatic. However, the automatic will still usually edge out a manual.

You could say that the other way around: The auto has the gearing advantage which offsets the manuals advantage of losing less power to the wheels...

If that's the case, should be very close in-gear acceleration between the two with the faster auto shifts taking the lead?

[travislambert]

Originally Posted by L99BEN

If that's the case, should be very close in-gear acceleration between the two with the faster auto shifts taking the lead?

That seems to hold true from what I've seen. I've driven manual transmission cars my whole life, but it's still hard not to give up ground to an automatic while shifting (It's even harder for a supercharged car that drops boost on a shift).

The original poster provides 40 to 120 MPH as the example. Assuming a second gear start on the manual, that's two shifts. It would be really close, especially if the manual driver shifts quickly. My money is still on the automatic for the win. (...but I would rather own the manual transmission car )

[hotlap]

Originally Posted by travislambert

The manual has a little less power loss through the transmission which mostly offsets the gearing advantage of the automatic. However, the automatic will still usually edge out a manual.

That statement is hard to quantify. We know one of the main design achievements in the 8L90 is its low speed efficiency. Manuals once had better fuel economy but that's not true today. Even though the A8's gearing is more aggressive, it offers better fuel economy across the entire range.

When equipped with the eight-speed automatic, the 455-hp 2016 Camaro SS V-8 returns 17/20/28 mpg city/combined/highway. The six-speed manual returns lower numbers at 16/19/25

http://www.motortrend.com/news/2016-...8-mpg-highway/

[ULTRAZLS1]

They sure aren't trapping any higher for average on these boards fast list (manuals). Old rule of thumb car that traps higher wins the roll race.

[travislambert]

Originally Posted by hotlap

That statement is hard to quantify. We know one of the main design achievements in the 8L90 is its low speed efficiency. Manuals once had better fuel economy but that's not true today. Even though the A8's gearing is more aggressive, it offers better fuel economy across the entire range.

I don't want to spend my evening digging up sources, but it's pretty well known that manual transmissions have less parasitic loss. Also, it's easy to see that an automatic has a gearing advantage. It may be hard to "quantify" the delta, but it's not difficult to see that the advantages nearly offset. If one advantage doesn't nearly offset the other, cars with the same horsepower and different gearing wouldn't even be comparable.

It's a bit of a leap to use EPA fuel economy ratings in a discussion about the transmission with an advantage in a roll race. (These EPA tests are a complete joke anyway. )

[hotlap]

Originally Posted by travislambert

I don't want to spend my evening digging up sources, but it's pretty well known that manual transmissions have less parasitic loss. Also, it's easy to see that an automatic has a gearing advantage. It may be hard to "quantify" the delta, but it's not difficult to see that the advantages nearly offset. If one advantage doesn't nearly offset the other, cars with the same horsepower and different gearing wouldn't even be comparable.

It's a bit of a leap to use EPA fuel economy ratings in a discussion about the transmission with an advantage in a roll race. (These EPA tests are a complete joke anyway. )

I am am only pointing out that it appears the 8-speed autos have narrowed or erased the efficiency gap. We've all seen re ent dyno runs followed by claims that manufactures are under rating the engines because we no longer see the historic 15% loss.

It has also been pretty well known that manuals get better fuel economy because they had less parasitic loss. That changed this generation.

[Dysan911]

Isn't that 1 mpg advantage of the A8 because of the AFM cylinder deactivation? That's something the M6 doesn't get.