M6 vs A6 for gas mileage?
06-10-2008, 09:36 AM
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M6 vs A6 for gas mileage? I'm not sure if this is the correct place for this or not. If it isn't then I apologize.
Which type of transmission gets better gas mileage an automatic or manual?
Assume that the car and the driving style is exactly the same for each car.
I'm specifically referring to the upcoming G8 GXP.
I'm on the fence about getting the M6 or the A6 but I'm leaning towards the M6. The bad thing is my wife wants me to get the A6 but she said, "it will be your car, get what YOU want" which usually means get what I said or you'll pay for it. If I can present a valid argument for the gas mileage then I can pull it off.
Here are the gear ratios.
*edit* I said that about my wife in jest. I am very fortunate to have found her so save any "wife mod" comments.
Which type of transmission gets better gas mileage an automatic or manual?
Assume that the car and the driving style is exactly the same for each car.
I'm specifically referring to the upcoming G8 GXP.
I'm on the fence about getting the M6 or the A6 but I'm leaning towards the M6. The bad thing is my wife wants me to get the A6 but she said, "it will be your car, get what YOU want" which usually means get what I said or you'll pay for it. If I can present a valid argument for the gas mileage then I can pull it off.
Here are the gear ratios.
*edit* I said that about my wife in jest. I am very fortunate to have found her so save any "wife mod" comments.
Last edited by 99-LS1-SS; 06-10-2008 at 10:04 AM.
06-10-2008, 11:42 AM
#2
TECH Fanatic
Driver makes almost all the difference here. If you leave the A6 in Drive the PCM knows exactly where to shift for best mileage and emissions. If you are rowing the stick, you have to concentrate 100% of the time to be in the "best" gear for max MPG. Even trained professional test drivers have trouble doing that.
Today's A6, A7, etc. transmissions are so efficient that even with good drivers there is very little difference in MPG. Additionally, with the trans and final drive ratios you quoted the M6 will spin about 8.6% faster in 6th on the highway. I don't think that will help the M6 beat the A6 in MPG.
Not what you wanted to hear, I'll bet. Don't let your better half see this thread, or at least this post.
Good luck!
Jon
Today's A6, A7, etc. transmissions are so efficient that even with good drivers there is very little difference in MPG. Additionally, with the trans and final drive ratios you quoted the M6 will spin about 8.6% faster in 6th on the highway. I don't think that will help the M6 beat the A6 in MPG.
Not what you wanted to hear, I'll bet. Don't let your better half see this thread, or at least this post.
Good luck!
Jon
06-10-2008, 12:02 PM
#3
http://www.f-body.org/gears/
for tire size of 275/40-17 or diameter of 25.66",
I know my 02 ss M6 with 0.5 6th gear ratio and 3.42 rear end turns 1500 rpm at 67mph.
for the same tire size-
the m6 above at .63 6th gear and 3.73 rear turns approx 2050 rpm at 67mph,
and the A6 with .67 6th gear and 3.23 rear turns 1900 rpm at 67 mph.
neglecting tire diameter which would be a constant offset unless the choice of auto vs. manual comes with different tires,
from an rpm standpoint I would guess the auto would give better highway mileage and you might reasonably assume near equal drivetrain loss at highway speed because of torque converter lockup. Generally there is always more parasitic loss (theoretically) in an auto transmission because of the transmission fluid pump and also if there's another pump in the torque converter (but I am no where near up to date on how auto transmissions are made currently so I'm somewhat speculating and could be somewhat wrong). But how much this has a real world affect could also be negligible, and may also be dependent on either rpm or speed.
you might also consider looking at the tq curve at the engine to help deduce if a lower rpm (even though only 200 rpm) could have a significant impact on fuel consumption. Or can a slightly higher rpm because the engine is at light load result in less fuel consumption (meaning lower rpm does not always equal less fuel consumption) ?
And I don't know what the mass of either trans is. If you can get just the weight of both trans and compare, and if the auto significantly heavier it could mean increased parasitic loss if that weight is dynamic as opposed to static.
with the lower rpm i would agree that it would be a hard sell to honestly say the manual would be more efficient and get better highway gas mileage in this case. but depending on your driving environment, like if it were in the city and if you can clutch in a lot of times and coast and get the engine to actually idle, you might be able to pull off better mileage. that's about the only plausible reason i can think of for the auto over the manual based on the numbers.
for tire size of 275/40-17 or diameter of 25.66",
I know my 02 ss M6 with 0.5 6th gear ratio and 3.42 rear end turns 1500 rpm at 67mph.
for the same tire size-
the m6 above at .63 6th gear and 3.73 rear turns approx 2050 rpm at 67mph,
and the A6 with .67 6th gear and 3.23 rear turns 1900 rpm at 67 mph.
neglecting tire diameter which would be a constant offset unless the choice of auto vs. manual comes with different tires,
from an rpm standpoint I would guess the auto would give better highway mileage and you might reasonably assume near equal drivetrain loss at highway speed because of torque converter lockup. Generally there is always more parasitic loss (theoretically) in an auto transmission because of the transmission fluid pump and also if there's another pump in the torque converter (but I am no where near up to date on how auto transmissions are made currently so I'm somewhat speculating and could be somewhat wrong). But how much this has a real world affect could also be negligible, and may also be dependent on either rpm or speed.
you might also consider looking at the tq curve at the engine to help deduce if a lower rpm (even though only 200 rpm) could have a significant impact on fuel consumption. Or can a slightly higher rpm because the engine is at light load result in less fuel consumption (meaning lower rpm does not always equal less fuel consumption) ?
And I don't know what the mass of either trans is. If you can get just the weight of both trans and compare, and if the auto significantly heavier it could mean increased parasitic loss if that weight is dynamic as opposed to static.
with the lower rpm i would agree that it would be a hard sell to honestly say the manual would be more efficient and get better highway gas mileage in this case. but depending on your driving environment, like if it were in the city and if you can clutch in a lot of times and coast and get the engine to actually idle, you might be able to pull off better mileage. that's about the only plausible reason i can think of for the auto over the manual based on the numbers.
Last edited by 1 FMF; 06-10-2008 at 12:24 PM.
06-10-2008, 09:16 PM
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it'll be tough call
with freeway driving, the M6 should get better mileage due to a few factors
no pumping losses like the auto, spur gears are more efficient than planetary, but the engine will spin faster due to the 3.73 final drive.. so that takes more engine friction
However, once you get in town, its much easier to get worse mileage.. typically you hold a gear too long and have excess engine friction losses. (same reason they had skip shift in the T-56 Fbodies).
i will say that any steady state point the manual transmission will be more efficient, however, the human factor is the most unpredictable..
So, i guess there really is no "true" answer
with freeway driving, the M6 should get better mileage due to a few factors
no pumping losses like the auto, spur gears are more efficient than planetary, but the engine will spin faster due to the 3.73 final drive.. so that takes more engine friction
However, once you get in town, its much easier to get worse mileage.. typically you hold a gear too long and have excess engine friction losses. (same reason they had skip shift in the T-56 Fbodies).
i will say that any steady state point the manual transmission will be more efficient, however, the human factor is the most unpredictable..
So, i guess there really is no "true" answer
06-10-2008, 09:29 PM
#5
Damn, you know gas prices are high when a question that would otherwise be flamed as "not technical" actually elicits responses that makes it appropriate for this forum. However, even if someone plotted the BSFC of their motor across every rpm range and logged their driving habits, those transmissions will be so close that one chance encounter with a stoplight race could skew the results either way.
06-10-2008, 09:41 PM
#6
TECH Fanatic
Here is an article excerpted from the May 2008 issue of Ward's AutoWorld trade magazine. The bold is mine. There is a lot more interesting info slightly OT, so it's shown smaller.
It's An Efficiency Thing
Since the dawn of the automobile, the mechanically pure manual transmission has ruled the roost in terms of efficiency. GM's 1940 innovation of the planetary automatic brought comfort and convenience, but its torque converter also introduced plenty of fuel-sapping drag.
Now, an important factor in future transmission implementation is the fact that the relative efficiency of new-technology transmissions is converging around a theoretical optimum overall ratio spread of roughly 6:1.
In effect, today's multi-speed automatics are closing in on the renowned efficiency of the manual transmission — and the DCT for that matter, as the DCT's foundation architecture is that of a conventional manual.
Southwest Research Institute has a longstanding competency in transmission testing and evaluation, and SwRI's Castiglione says, “For contemporary front-wheel-drive 6-speed automatic transmissions, we are seeing maximum efficiencies of around 93% to 94%. For rear-wheel-drive 6-speed automatics, we have measured maximum efficiencies of up to 97%.
“The continued development of electronic pressure controls and torque converter lock-up strategies has increased the efficiencies of transmissions,” he adds. “These developments, along with other design improvements, have allowed the manufacturers to increase the number of gears without reducing efficiency. The addition of more forward gears allows the engine to operate in a narrower speed range, which reduces fuel consumption.”
The end result for today's new generation of multi-speed planetary automatics is remarkable. ZF data shows a striking increase in fuel-efficiency for a 6-speed automatic compared with a 4- or 5-speed. And although we once were told there was little to be gained from expanding beyond six ratios, ZF's figures indicate otherwise.
That explains ZF's pending jump to the 8-speed paradigm, along with Aisin Group, which already has an 8-speed planetary automatic in production for Toyota Motor Corp.'s Lexus Div. These two transmission suppliers, as well as Japan's Jatco Ltd. and OEMs Volkswagen, Ford and GM, all are licensees of the pioneering Lepelletier 6-speed architecture, of which most 7- and 8-speeds will be a derivation.
ZF's Paul says the efficiency of the company's new 8-speed automatic will close the gap with DCTs, which are claimed to be some 10%-15% more efficient than a 6-speed automatic.
ZF unveiled its 8-speed automatic at February's Geneva auto show in intriguing “hybridized” form in the BMW X5 Vision, but a production version isn't expected until sometime next year, perhaps for a '10 model likely to be a BMW.
ZF says the 8-speed employs an “entirely new shifting concept” of four planetary gear sets and five shift elements — and improves fuel economy by 6% over the still-new 6 HP 28 6-speed unit. ZF also says the new unit can handle more torque than its 6-speed automatic, although the 8-speed enjoys similar weight and dimensions.
Significantly, Paul says the 8-speed automatic's overall ratio spread is slightly better than 7:1. He says depending on the torque characteristics of future engines, there may be an opportunity for planetary automatics to move to an even wider ratio spread, but “we are close to the optimum.”
Look for efficiency and performance improvements from DCTs to counter the surge from 8-speed automatics, however.
BorgWarner's Matthes says 7- and 8-speed planetary automatics may catch up to the efficiency of today's 6-speed DCTs, but a second generation will improve on the company's current wet-clutch DCT design with a “humid” architecture with advanced friction materials.
The new gearbox requires much less lubricating oil, while also leveraging higher-pressure control modules, both intended to boost efficiency. With the humid clutch, “we aren't taking a bath, we're taking a shower,” Matthes says in explaining the humid DCT's lubrication strategy.
There could be additional ratios, as well, as is the case with BMW's all-new 7-speed DCT, although Matthes says most vehicles could not make productive use of 7- or 8-speed DCTs.
He says the humid-DCT design also takes the architecture a step closer to the dry clutch, which is more efficient but has much lower torque capacities. Earlier this year, BorgWarner introduced its first dry-clutch DCT, a 7-speed unit going into service for VW.
What about hybridization? ZF (through BMW) unveiled its 8-speed by highlighting its modular design that enables incorporation of an electric motor directly in the transmission. It's likely more multi-speed automatics will include this feature, doubtless inspired by the 2-mode hybrid transmission jointly developed by GM, BMW and the former DaimlerChrysler AG.
But here, Matthes insists the DCT also enjoys an advantage, calling its layout the “perfect link” for a hybrid driveline. He says the design of the DCT, with two input shafts, is ideal for dividing and controlling the separate internal-combustion and electric-drive components of a hybrid.
It's An Efficiency Thing
Since the dawn of the automobile, the mechanically pure manual transmission has ruled the roost in terms of efficiency. GM's 1940 innovation of the planetary automatic brought comfort and convenience, but its torque converter also introduced plenty of fuel-sapping drag.
Now, an important factor in future transmission implementation is the fact that the relative efficiency of new-technology transmissions is converging around a theoretical optimum overall ratio spread of roughly 6:1.
In effect, today's multi-speed automatics are closing in on the renowned efficiency of the manual transmission — and the DCT for that matter, as the DCT's foundation architecture is that of a conventional manual.
Southwest Research Institute has a longstanding competency in transmission testing and evaluation, and SwRI's Castiglione says, “For contemporary front-wheel-drive 6-speed automatic transmissions, we are seeing maximum efficiencies of around 93% to 94%. For rear-wheel-drive 6-speed automatics, we have measured maximum efficiencies of up to 97%.
“The continued development of electronic pressure controls and torque converter lock-up strategies has increased the efficiencies of transmissions,” he adds. “These developments, along with other design improvements, have allowed the manufacturers to increase the number of gears without reducing efficiency. The addition of more forward gears allows the engine to operate in a narrower speed range, which reduces fuel consumption.”
The end result for today's new generation of multi-speed planetary automatics is remarkable. ZF data shows a striking increase in fuel-efficiency for a 6-speed automatic compared with a 4- or 5-speed. And although we once were told there was little to be gained from expanding beyond six ratios, ZF's figures indicate otherwise.
That explains ZF's pending jump to the 8-speed paradigm, along with Aisin Group, which already has an 8-speed planetary automatic in production for Toyota Motor Corp.'s Lexus Div. These two transmission suppliers, as well as Japan's Jatco Ltd. and OEMs Volkswagen, Ford and GM, all are licensees of the pioneering Lepelletier 6-speed architecture, of which most 7- and 8-speeds will be a derivation.
ZF's Paul says the efficiency of the company's new 8-speed automatic will close the gap with DCTs, which are claimed to be some 10%-15% more efficient than a 6-speed automatic.
ZF unveiled its 8-speed automatic at February's Geneva auto show in intriguing “hybridized” form in the BMW X5 Vision, but a production version isn't expected until sometime next year, perhaps for a '10 model likely to be a BMW.
ZF says the 8-speed employs an “entirely new shifting concept” of four planetary gear sets and five shift elements — and improves fuel economy by 6% over the still-new 6 HP 28 6-speed unit. ZF also says the new unit can handle more torque than its 6-speed automatic, although the 8-speed enjoys similar weight and dimensions.
Significantly, Paul says the 8-speed automatic's overall ratio spread is slightly better than 7:1. He says depending on the torque characteristics of future engines, there may be an opportunity for planetary automatics to move to an even wider ratio spread, but “we are close to the optimum.”
Look for efficiency and performance improvements from DCTs to counter the surge from 8-speed automatics, however.
BorgWarner's Matthes says 7- and 8-speed planetary automatics may catch up to the efficiency of today's 6-speed DCTs, but a second generation will improve on the company's current wet-clutch DCT design with a “humid” architecture with advanced friction materials.
The new gearbox requires much less lubricating oil, while also leveraging higher-pressure control modules, both intended to boost efficiency. With the humid clutch, “we aren't taking a bath, we're taking a shower,” Matthes says in explaining the humid DCT's lubrication strategy.
There could be additional ratios, as well, as is the case with BMW's all-new 7-speed DCT, although Matthes says most vehicles could not make productive use of 7- or 8-speed DCTs.
He says the humid-DCT design also takes the architecture a step closer to the dry clutch, which is more efficient but has much lower torque capacities. Earlier this year, BorgWarner introduced its first dry-clutch DCT, a 7-speed unit going into service for VW.
What about hybridization? ZF (through BMW) unveiled its 8-speed by highlighting its modular design that enables incorporation of an electric motor directly in the transmission. It's likely more multi-speed automatics will include this feature, doubtless inspired by the 2-mode hybrid transmission jointly developed by GM, BMW and the former DaimlerChrysler AG.
But here, Matthes insists the DCT also enjoys an advantage, calling its layout the “perfect link” for a hybrid driveline. He says the design of the DCT, with two input shafts, is ideal for dividing and controlling the separate internal-combustion and electric-drive components of a hybrid.
06-10-2008, 09:52 PM
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Here is an article excerpted from the May 2008 issue of Ward's AutoWorld trade magazine. The bold is mine. There is a lot more interesting info slightly OT, so it's shown smaller.
It's An Efficiency Thing
Since the dawn of the automobile, the mechanically pure manual transmission has ruled the roost in terms of efficiency. GM's 1940 innovation of the planetary automatic brought comfort and convenience, but its torque converter also introduced plenty of fuel-sapping drag.
Now, an important factor in future transmission implementation is the fact that the relative efficiency of new-technology transmissions is converging around a theoretical optimum overall ratio spread of roughly 6:1.
In effect, today's multi-speed automatics are closing in on the renowned efficiency of the manual transmission — and the DCT for that matter, as the DCT's foundation architecture is that of a conventional manual.
Southwest Research Institute has a longstanding competency in transmission testing and evaluation, and SwRI's Castiglione says, “For contemporary front-wheel-drive 6-speed automatic transmissions, we are seeing maximum efficiencies of around 93% to 94%. For rear-wheel-drive 6-speed automatics, we have measured maximum efficiencies of up to 97%.
“The continued development of electronic pressure controls and torque converter lock-up strategies has increased the efficiencies of transmissions,” he adds. “These developments, along with other design improvements, have allowed the manufacturers to increase the number of gears without reducing efficiency. The addition of more forward gears allows the engine to operate in a narrower speed range, which reduces fuel consumption.”
The end result for today's new generation of multi-speed planetary automatics is remarkable. ZF data shows a striking increase in fuel-efficiency for a 6-speed automatic compared with a 4- or 5-speed. And although we once were told there was little to be gained from expanding beyond six ratios, ZF's figures indicate otherwise.
That explains ZF's pending jump to the 8-speed paradigm, along with Aisin Group, which already has an 8-speed planetary automatic in production for Toyota Motor Corp.'s Lexus Div. These two transmission suppliers, as well as Japan's Jatco Ltd. and OEMs Volkswagen, Ford and GM, all are licensees of the pioneering Lepelletier 6-speed architecture, of which most 7- and 8-speeds will be a derivation.
ZF's Paul says the efficiency of the company's new 8-speed automatic will close the gap with DCTs, which are claimed to be some 10%-15% more efficient than a 6-speed automatic.
ZF unveiled its 8-speed automatic at February's Geneva auto show in intriguing “hybridized” form in the BMW X5 Vision, but a production version isn't expected until sometime next year, perhaps for a '10 model likely to be a BMW.
ZF says the 8-speed employs an “entirely new shifting concept” of four planetary gear sets and five shift elements — and improves fuel economy by 6% over the still-new 6 HP 28 6-speed unit. ZF also says the new unit can handle more torque than its 6-speed automatic, although the 8-speed enjoys similar weight and dimensions.
Significantly, Paul says the 8-speed automatic's overall ratio spread is slightly better than 7:1. He says depending on the torque characteristics of future engines, there may be an opportunity for planetary automatics to move to an even wider ratio spread, but “we are close to the optimum.”
Look for efficiency and performance improvements from DCTs to counter the surge from 8-speed automatics, however.
BorgWarner's Matthes says 7- and 8-speed planetary automatics may catch up to the efficiency of today's 6-speed DCTs, but a second generation will improve on the company's current wet-clutch DCT design with a “humid” architecture with advanced friction materials.
The new gearbox requires much less lubricating oil, while also leveraging higher-pressure control modules, both intended to boost efficiency. With the humid clutch, “we aren't taking a bath, we're taking a shower,” Matthes says in explaining the humid DCT's lubrication strategy.
There could be additional ratios, as well, as is the case with BMW's all-new 7-speed DCT, although Matthes says most vehicles could not make productive use of 7- or 8-speed DCTs.
He says the humid-DCT design also takes the architecture a step closer to the dry clutch, which is more efficient but has much lower torque capacities. Earlier this year, BorgWarner introduced its first dry-clutch DCT, a 7-speed unit going into service for VW.
What about hybridization? ZF (through BMW) unveiled its 8-speed by highlighting its modular design that enables incorporation of an electric motor directly in the transmission. It's likely more multi-speed automatics will include this feature, doubtless inspired by the 2-mode hybrid transmission jointly developed by GM, BMW and the former DaimlerChrysler AG.
But here, Matthes insists the DCT also enjoys an advantage, calling its layout the “perfect link” for a hybrid driveline. He says the design of the DCT, with two input shafts, is ideal for dividing and controlling the separate internal-combustion and electric-drive components of a hybrid.
It's An Efficiency Thing
Since the dawn of the automobile, the mechanically pure manual transmission has ruled the roost in terms of efficiency. GM's 1940 innovation of the planetary automatic brought comfort and convenience, but its torque converter also introduced plenty of fuel-sapping drag.
Now, an important factor in future transmission implementation is the fact that the relative efficiency of new-technology transmissions is converging around a theoretical optimum overall ratio spread of roughly 6:1.
In effect, today's multi-speed automatics are closing in on the renowned efficiency of the manual transmission — and the DCT for that matter, as the DCT's foundation architecture is that of a conventional manual.
Southwest Research Institute has a longstanding competency in transmission testing and evaluation, and SwRI's Castiglione says, “For contemporary front-wheel-drive 6-speed automatic transmissions, we are seeing maximum efficiencies of around 93% to 94%. For rear-wheel-drive 6-speed automatics, we have measured maximum efficiencies of up to 97%.
“The continued development of electronic pressure controls and torque converter lock-up strategies has increased the efficiencies of transmissions,” he adds. “These developments, along with other design improvements, have allowed the manufacturers to increase the number of gears without reducing efficiency. The addition of more forward gears allows the engine to operate in a narrower speed range, which reduces fuel consumption.”
The end result for today's new generation of multi-speed planetary automatics is remarkable. ZF data shows a striking increase in fuel-efficiency for a 6-speed automatic compared with a 4- or 5-speed. And although we once were told there was little to be gained from expanding beyond six ratios, ZF's figures indicate otherwise.
That explains ZF's pending jump to the 8-speed paradigm, along with Aisin Group, which already has an 8-speed planetary automatic in production for Toyota Motor Corp.'s Lexus Div. These two transmission suppliers, as well as Japan's Jatco Ltd. and OEMs Volkswagen, Ford and GM, all are licensees of the pioneering Lepelletier 6-speed architecture, of which most 7- and 8-speeds will be a derivation.
ZF's Paul says the efficiency of the company's new 8-speed automatic will close the gap with DCTs, which are claimed to be some 10%-15% more efficient than a 6-speed automatic.
ZF unveiled its 8-speed automatic at February's Geneva auto show in intriguing “hybridized” form in the BMW X5 Vision, but a production version isn't expected until sometime next year, perhaps for a '10 model likely to be a BMW.
ZF says the 8-speed employs an “entirely new shifting concept” of four planetary gear sets and five shift elements — and improves fuel economy by 6% over the still-new 6 HP 28 6-speed unit. ZF also says the new unit can handle more torque than its 6-speed automatic, although the 8-speed enjoys similar weight and dimensions.
Significantly, Paul says the 8-speed automatic's overall ratio spread is slightly better than 7:1. He says depending on the torque characteristics of future engines, there may be an opportunity for planetary automatics to move to an even wider ratio spread, but “we are close to the optimum.”
Look for efficiency and performance improvements from DCTs to counter the surge from 8-speed automatics, however.
BorgWarner's Matthes says 7- and 8-speed planetary automatics may catch up to the efficiency of today's 6-speed DCTs, but a second generation will improve on the company's current wet-clutch DCT design with a “humid” architecture with advanced friction materials.
The new gearbox requires much less lubricating oil, while also leveraging higher-pressure control modules, both intended to boost efficiency. With the humid clutch, “we aren't taking a bath, we're taking a shower,” Matthes says in explaining the humid DCT's lubrication strategy.
There could be additional ratios, as well, as is the case with BMW's all-new 7-speed DCT, although Matthes says most vehicles could not make productive use of 7- or 8-speed DCTs.
He says the humid-DCT design also takes the architecture a step closer to the dry clutch, which is more efficient but has much lower torque capacities. Earlier this year, BorgWarner introduced its first dry-clutch DCT, a 7-speed unit going into service for VW.
What about hybridization? ZF (through BMW) unveiled its 8-speed by highlighting its modular design that enables incorporation of an electric motor directly in the transmission. It's likely more multi-speed automatics will include this feature, doubtless inspired by the 2-mode hybrid transmission jointly developed by GM, BMW and the former DaimlerChrysler AG.
But here, Matthes insists the DCT also enjoys an advantage, calling its layout the “perfect link” for a hybrid driveline. He says the design of the DCT, with two input shafts, is ideal for dividing and controlling the separate internal-combustion and electric-drive components of a hybrid.
Very nice posts, Old SStroker!
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06-11-2008, 05:47 AM
#9
TECH Resident
Generally the VE Commodore (the G8), turns better mpg with the A6, at least in the fuel consumption tests. As another poster mentioned, the gearing is quite close, and the shifts are optimised, consistent, adaptive and get you to the highest gear as early as possible.
They are also quite quick. reasonably easy mid 13's off the show room floor.
SS Enforcer on this forum has the quickest NA Auto VE at present: 11.8 in the quarter. Small cam, headers, exhaust, heads, tune, drag radials, stock A6 trans. 11.8 consistent.
They are also quite quick. reasonably easy mid 13's off the show room floor.
SS Enforcer on this forum has the quickest NA Auto VE at present: 11.8 in the quarter. Small cam, headers, exhaust, heads, tune, drag radials, stock A6 trans. 11.8 consistent.
06-11-2008, 08:45 PM
#10
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The thing you will find is
Programmed and tested transmission calibrations will trump human shifted transmissions 95%+ of the time (given current technology in a city environment)
People with highly instrumented engines and transmissions will always beable to make it operate in the best BSFC zone at all times.. I find that alot of times "what feels like the right gear" may not always be the best for fuel economy..
Steady state speed, i think there is still room for argument however..
SWRI is a great place..
Programmed and tested transmission calibrations will trump human shifted transmissions 95%+ of the time (given current technology in a city environment)
People with highly instrumented engines and transmissions will always beable to make it operate in the best BSFC zone at all times.. I find that alot of times "what feels like the right gear" may not always be the best for fuel economy..
Steady state speed, i think there is still room for argument however..
SWRI is a great place..
Last edited by DanO; 06-11-2008 at 08:53 PM.
06-11-2008, 09:44 PM
#11
TECH Resident
The thing you will find is
Programmed and tested transmission calibrations will trump human shifted transmissions 95%+ of the time (given current technology in a city environment)
People with highly instrumented engines and transmissions will always beable to make it operate in the best BSFC zone at all times.. I find that alot of times "what feels like the right gear" may not always be the best for fuel economy..
Steady state speed, i think there is still room for argument however..
SWRI is a great place..
Programmed and tested transmission calibrations will trump human shifted transmissions 95%+ of the time (given current technology in a city environment)
People with highly instrumented engines and transmissions will always beable to make it operate in the best BSFC zone at all times.. I find that alot of times "what feels like the right gear" may not always be the best for fuel economy..
Steady state speed, i think there is still room for argument however..
SWRI is a great place..
With instrumentation now including instantaneous fuel consumption readouts, the sooner you can get to a higher gear without lugging, the lower the fuel consumption. I try and explain this to my wife. She still doesn't use the overdrive gear and uses 1 - 2mpg more fuel. And lugs.
SWRI?
06-12-2008, 07:26 AM
#12
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So...due to the fact that I don't drive at a steady speed for more than a minute or two on a regular basis I would be better off with an automatic transmission. That hurts the kid in me but I'm now officially leaning towards the automatic transmission.
Thanks again to everyone that posted and if anyone has something else to add please do so.
Thanks again to everyone that posted and if anyone has something else to add please do so.
06-14-2008, 01:19 PM
#15
Agreed on the human factor ... when driving my M6, I typically shift 500rpm or higher than my A4 would shift. Dunno why, it's just what "feels right."
Another factor for highway driving is the cylinder deactivation (or whatever they're calling it now) on the A6.
There was no contest A4 vs. M6 - the M6 was much better. But in today's A6 world I think the results are going to be very close. It'll be interesting to see how the EPA numbers compare - although that's the opposite of "real world."
Another factor for highway driving is the cylinder deactivation (or whatever they're calling it now) on the A6.
There was no contest A4 vs. M6 - the M6 was much better. But in today's A6 world I think the results are going to be very close. It'll be interesting to see how the EPA numbers compare - although that's the opposite of "real world."
