[Allpar News System]

Allpar reader mentalicca discovered that EPA ratings for the Compass, Patriot, and Grand Cherokee SRT8 have been updated. They show that the six-speed automatic added around 1 mpg highway on the Compass and Patriot, over the CVT; and that the eight-speed pushed the Grand Cherokee SRT8 up to 13 city, 19 highway, an increase of 1 mpg in both city and highway mileage. The CVT was advertised as having superior gas mileage versus conventional automatics, but at the time it was being compared to four-speeds with relatively low ranges; the greater overdrive of the Hyundai six-speed most likely overcame inherent efficiencies of the CVT on the highway, even as it delivered a generally preferred driving experience.  The real surprise of the group was the relatively small gas-mileage boost of the eight-speed automatic when coupled with the 470 horsepower SRT8 engine. Still, at a typical 12,000 miles per year, the transmission..

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[bumonbox]

The Hemi engines as a whole seem to not get nearly the benefit the Pentastar gets. Note that the 5.7 equipped Ram sees a pretty meager jump. Norm pointed out the the nature of the V6 makes a more logical pairing the 8 spd, this likely helps explain the delay of the 8 spd in the LXs. I suspect it will still be an improvement in every day driving. I kind of suspect that MDS could be revised to better leverage the 8 spd, accounting for more favorable gearing and what not. But, alas, the Hemi equipped vehicles are much less in the spot light these days.

As for the Compass / Patriot, not surprised.

 

[mentalicca]

The Hemi engines as a whole seem to not get nearly the benefit the Pentastar gets. Note that the 5.7 equipped Ram sees a pretty meager jump. Norm pointed out the the nature of the V6 makes a more logical pairing the 8 spd, this likely helps explain the delay of the 8 spd in the LXs. I suspect it will still be an improvement in every day driving. I kind of suspect that MDS could be revised to better leverage the 8 spd, accounting for more favorable gearing and what not. But, alas, the Hemi equipped vehicles are much less in the spot light these days.

As for the Compass / Patriot, not surprised.

With regard to that, I never saw the actual Ram 5.7 MPG yet, but it was allegedly 22MPG highway right? If so, that's still a 10% jump in highway.

The other thing I am curious about is how they round the MPG. I'm sure there is a doc specifying if they must round down, or they can round to the nearest, or something of that nature. Either way that probably explains the only 1mpg on paper for the SRT8, it may have been a 10% increase too. That being said, it also seems as though the hemi grand cherokee mileage boost with the 8 speed is less than the equivalent Ram.

 

[link3721]

My first thought is...can I replace my CVT with the 6 speed in my older Patriot? Wonder how difficult that would be...

 

[AutoTechnician]

bumonbox, on 22 Feb 2013 - 09:56, said:
The Hemi engines as a whole seem to not get nearly the benefit the Pentastar gets. Note that the 5.7 equipped Ram sees a pretty meager jump. Norm pointed out the the nature of the V6 makes a more logical pairing the 8 spd, this likely helps explain the delay of the 8 spd in the LXs. I suspect it will still be an improvement in every day driving. I kind of suspect that MDS could be revised to better leverage the 8 spd, accounting for more favorable gearing and what not. But, alas, the Hemi equipped vehicles are much less in the spot light these days.

As for the Compass / Patriot, not surprised.

I would not call a 2 MPG jump across the board "meager". That's a 13% increase in city fuel economy, and a 10% increase in highway. Those are HUGE gains.

 

[Mike V.]

I would not call a 2 MPG jump across the board "meager". That's a 13% increase in city fuel economy, and a 10% increase in highway. Those are HUGE gains.

Agreed :thumbsup:

 

[bumonbox]

I would not call a 2 MPG jump across the board "meager". That's a 13% increase in city fuel economy, and a 10% increase in highway. Those are HUGE gains.

For some reason, I recalled only a 1 MPG jump, perhaps that is the GC. I thought the GC only sees 21 MPG on RWD with the Hemi, maybe the Ram does better.
If it is 22, then it's darn decent, especially for just changing the trans. But, what I was saying is not as substantial as with the Pentastar in most configs.

I am not dismissing it though, I didn't mean to come off that way, and it will definitely help all of the vehicles that gain it.

 

[Dave Z]

Right, Pentastar jumped what, 4 mpg highway? I thought the 6.4 would benefit more since it just loafs around much of the time Higher overdrive would mean, I thought, four cylinders cut off more often.

But yeah, remember this? http://www.allpar.com/news/index.php/2013/02/fuel-savings-depend-on-the-starting-point

 

[Stratuscaster]

2013 Jeep Patriot 2WD - 2.0L/CVT2: 22/28(24)
2014 Jeep Patriot 2WD - 2.0L/6auto: 21/28(24)

2013 Jeep Patriot 2WD - 2.4L/CVT2: 21/27(24)
2014 Jeep Patriot 2WD - 2.4L/6auto: 21/28(24)

2013 Jeep Patriot FD1 - 2.4/CVT2: 21/26(23)
2014 Jeep Patriot FD1 - 2.4/6auto: 21/27(23)

The improvement here isn't for MPG - it's for NVH and "feel".

 

[dana44]

I would think the computer would be the most difficult part of the swap.

 

[red-jk]

With regard to that, I never saw the actual Ram 5.7 MPG yet, but it was allegedly 22MPG highway right? If so, that's still a 10% jump in highway.

I regularly get 22MPG highway on my 2011 RAM with the 5spd. I would expect more out of the 8spd.

 

[guyverfanboy]

I am curious what the mileage will be in the LX cars 300/Charger/Challenger with HEMI and 8-speed.

 

[Stratuscaster]

I'd guess 17/25(20).

 

[drew54]

We know they had to EPA and crash these cars to get them certified. If they are willing to build these cars with the new transmission for just a few years to gain 1 MPG, then IMO we should stop using it as an excuse for other vehicles not receiving updates. Besides, can't these tests be used as a tax write off.