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Old 03-27-2011, 11:11 PM
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Auto or Sport - Fuel Efficiency

Hey, perhaps a stupid question, but which mode would be best for fuel efficiency. Sport mode as I am aware transfers 80% to the rear tires, making it almost a rear wheel drive. So would sport mode be better for fuel efficiency?
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Old 03-28-2011, 02:36 AM
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Re: Auto or Sport - Fuel Efficiency

Im pretty sure auto would be the most fuel efficient. As not only does sport transfer power more to the rear but it also changes timing and whatnot to make the jeep more aggressive, from what I understand anyways.
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Old 03-28-2011, 03:38 AM
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Re: Auto or Sport - Fuel Efficiency

Sport mode shifts the bias to rear wheel torque distribution, but you're still in 4WD so there is no fuel economy improvement. Auto mode and soft on the throttle (hard to do) is the best for mileage.
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Old 03-28-2011, 05:52 AM
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Re: Auto or Sport - Fuel Efficiency

Unless someone can point to specific information from Jeep that contradicts what's printed in the manual then all sport mode does is:

SPORT

Traction Control Limited
Up to 80% rear drive torque split
Air Suspension at AERO (if equipped)

Or, to be more precise:

Quote:
Sport – Dry weather, on-road calibration. Only available
in 4WD High range. Performance based tuning
that provides a rear wheel drive feel but with improved
handling and acceleration over a two-wheel
drive vehicle. The Electronic Stability Control will set to
allow more driver control of vehicle while maintaining
safe handling controls. The vehicle will lower (if
equipped with Air Suspension) to Aero Mode in High
Range. 4WD Low is not available in SPORT mode, if
4WD Low is selected the Selec-Terrain™ will automatically
switch back to AUTO.
There's nothing documented that indicates it does anything to the ignition timing, shift patterns or anything related to the engine/trans. Done confuse the comments on performance based tuning to mean engine tuning, they are only talking about the select-terrain system, not the engine or trans.

So, basically it should have no effect on mileage.
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Old 03-28-2011, 08:42 AM
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Re: Auto or Sport - Fuel Efficiency

Quote:
Originally Posted by mjw930 View Post
Unless someone can point to specific information from Jeep that contradicts what's printed in the manual then all sport mode does is:

SPORT

Traction Control Limited
Up to 80% rear drive torque split
Air Suspension at AERO (if equipped)

Or, to be more precise:



There's nothing documented that indicates it does anything to the ignition timing, shift patterns or anything related to the engine/trans. Done confuse the comments on performance based tuning to mean engine tuning, they are only talking about the select-terrain system, not the engine or trans.

So, basically it should have no effect on mileage.
Have you spent time behind the wheel and tried both Sport and Auto. The manual may not say anything about it but it does have a faster tip-in.
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Old 03-28-2011, 08:57 AM
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Re: Auto or Sport - Fuel Efficiency

Quote:
Originally Posted by 2011RitterGC View Post
Have you spent time behind the wheel and tried both Sport and Auto. The manual may not say anything about it but it does have a faster tip-in.
x2

The gas pedal seems more "responsive" and it is a lot quicker to downshift the transmission. In auto mode, it seems to want to hold the higher gear, put it in sport mode and as soon as you hit the gas, it is getting into the correct gear.
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Old 03-28-2011, 10:08 AM
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Re: Auto or Sport - Fuel Efficiency

I tried sport mode yesterday and the "traction control off" light turned on.
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Old 03-28-2011, 10:57 AM
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Re: Auto or Sport - Fuel Efficiency

It also seems to hold gears longer before shifting. There is definitely a difference in the shifting and tip in.
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Old 03-28-2011, 10:59 AM
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Re: Auto or Sport - Fuel Efficiency

Thanks for the input Auto it is then. Strange, I am averaging 17.5L/100km (mostly city drive) on a 3.6L overland well beyond the 13L/100km as Chrysler advertises. Perhaps the engine needs to be broken in first? I am at 1500km....
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Old 03-28-2011, 12:08 PM
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Re: Auto or Sport - Fuel Efficiency

Yes, I've spent plenty of time in each mode and I think you're feeling what you want to feel. I suspect most of what you consider tip in or responsiveness is the change to the traction control. Usually, if there is a change to the engine or trans program they would make a big deal about it, they don't. Until it's confirmed by either a Jeep engineer or one of the aftermarket tuners I stand by my belief there's no modification to the overall engine and trans program and the setting has zero effect on MPG.
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Old 03-28-2011, 01:17 PM
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Re: Auto or Sport - Fuel Efficiency

Quote:
Originally Posted by mjw930 View Post
Until it's confirmed by either a Jeep engineer or one of the aftermarket tuners I stand by my belief there's no modification to the overall engine and trans program and the setting has zero effect on MPG.
The throttle sensitivity is certainly affected in Low Range and in Snow mode and the transmission shift points are definitely altered in Tow/Haul, so that indicates that indeed the engine (throttle) and transmission programming are both affected by using the various settings. In AUTO mode, per Jeep documentation, the vehicle switches to various modes as needed without user input (except for Low). Snow mode and Low range greatly subdues throttle response...and it makes sense given their purpose. There is more going on than just adjusting the torque split in the transfer case.

I've tried all the modes in just about every condition short of a sand dune and there is absolutely a difference in throttle sensitivity and transmission shift points between Snow and Sport, for example. The only thing I would agree with is that fuel economy is indeed not affected when choosing a different mode given the same road condition with the exception of using Low (obviously) or Tow/Haul mode.

As Tow/Haul I believe relates, the Tow/Haul switch not only locks out the top overdrive ratio but, unless I hallucinate, at various throttle inputs it raises the rpm shift points under normal loads as well as when towing except under full throttle where the shifts are all maximized. Also, I experience Sport mode downshifting more readily as well as making the throttle more responsive to provide the lively "rear drive feel" as documented when using that mode.
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Old 03-28-2011, 01:43 PM
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Re: Auto or Sport - Fuel Efficiency

I suppose it's subtle and depends on the situation. Of course snow and low range change the throttle response, it's documented they do.

Tow/Haul actually uses an underdrive to make each gear slightly taller (numerically) on the "multi-speed" transmission with the 5.7L. That would have the net effect of changing the shift points.

Overall the powertrain is pretty darn sophisticated when you factor in the tow / haul mode underdrive, 2nd prime for downshifting and the ability to control the top gear the trans will select. I'll even give in a little to the sport mode effecting throttle sensitivity but I"m nto 100% sold it changing the shift points.

Regardless the fine details I think we can come to a general consensus that simply choosing Sport over Auto will probably not have a measurable effect on MPG, Correct?
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