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Hello.

Does anyone know how much powertrain loss there is in the 6 speed automatic transmission in the Cruze? It would be interesting to know how much horsepower actually makes it to the pavement. Thanks.
 

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Automatic transmissions are built for smooth shifting at low RPM's 2-3K when driving normally. So being that sometimes your limited to low RPM's, you don't really lose any horsepower just that you shouldn't expect a lot of horsepower at low RPM's. If you floor it and hit 4k or more you will get most of the car's horsepower.

6 Speed auto's have a shorter gear ratio which give you the benefit of more horsepower over the typical 4 or 5 speed auto's. So be happy you have a 6 speed.
 

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..."rule-of-thumb" for automatic transmissions is about 15% loss (10% for manuals), so it's 'in the ballpark.'
 

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...somewhere, I have a GM paper where the "old" 3-speed HydraMatic tranny was dyno-tested at 85% power transfer.

...true, that's not a 6-speed, but it is representative of HM's in general.
 

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...driver has more/better control of engine speed and power with a manual transmission.

...that's typically not so with automatic transmissions, although the "new" paddle and double-plate (vs. slush box) automatics can almost equal a manual.

...automatics only become "good" when their torque-converter is 100% "locked" which the driver seldom has control over.
 

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I posted this on here somewhere, but I'm still a bit of a noob to these forums so I'll post again here too. I read somewhere that the manual Eco will be the one getting 42 mpg and an automatic Eco was actually around 36 or 38. First off, do you know anything about that and if it's true or not?
And secondly, I have a '94 Geo Prizm right now which is rated for 29 mpg highway. However I consistently achieve 40 to 41 mpg on the highway (well, not any more but that's an issue that's recently sprung up and it's not worth fixing). Should I be able to achieve 42 or even better on the highway in an auto still? I know the Eco is at least 600 pounds heavier so that makes me wonder.


Oh, and I found out recently that my Eco is being built the week of Feb 7th so I should have it the around the third week of Feb. VERY excited!
 

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...if you don't make "jackrabbit" starts, drive at reasonable (55-65 mph) speeds, learn to "read" traffic so as to anticipate stoplights and idiot drivers, you should be able to match or exceed the EPA values (city/highway):

• Eco 6-speed manual......28/42 mpg
• Eco 6-speed automatic...26/37 mpg
• 1LT,2LT,LTZ automatic...24/36 mpg

...many ecomodder drivers routinely get 50% over their EPA numbers.
 

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Man, that's kind of disappointing that the auto is so much lower than the manual. Oh well. Even with a 600+ pound heavier car than what I have now, I should still be able to get very good mileage. I do drive very smart and don't use my brakes if I don't have to. If I coast for an extended period of time, I'll pop the car out of gear into neutral. That uses less fuel and allows you to coast at a higher speed for longer. I am probably a borderline hypermiler/ecomiler/whatnot. I've been meaning to do some actual research on that.
 

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I am probably a borderline hypermiler/ecomiler/whatnot. I've been meaning to do some actual research on that.
...go visit ecomodder.com...I'm "Old Tele man" over there (and, apparently, the only poster there with a Cruze).
 

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Thanks for the link. I found a list of 100 things that save you fuel and unsurprisingly, I actually already do/know over 90% of them. I have a question for you though if it's not considered off topic. There's one listed:

Automatic transmission: neutral when stopped
Shift automatic transmissions to neutral when stopped (assuming you're going to leave the engine running). Remaining in drive wastes fuel as the engine continues to try to creep the car forward while being held back by the brakes.​
I've been basing my fuel consumption off of RPM speed. So shifting into neutral is actually better even at a higher RPM than being contained in drive?
And I know this is a non issue with the Cruze because it shifts into neutral when stopped.
 

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...except that 'some' GM electronic black boxes won't automatically shut-off fuel flow with the car moving and the transmission in neutral...it only does it when vehicle speed is zero...so, it's a "chicken vs. egg" condition: which saves more fuel: coasting with almost NO fuel being squirted or coasting with the engine at idle? I'm sure you know the answer.
 
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