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I have finished the data on 6 tests and will reveal my findings on how to drive the Auto R/T MDS.
I made 2 400 mile tests and 4 200 mile tests using the ecometer and good old fashion math calculated at the pump (same one, same place, same time of day). I did all this because I didn't believe those who posted the way to drive an auto in the city was with the autostick. Logic told me to creep up to speed and let the MDS take over at all possible times -4 cylinders better than 8, right?..WRONG. My sincere apologizes.
Without going into detail about all my tests with all auto stick, without, all mds on highway, without mds on highway, etc.., let me just put it out here for all to see. Some to believe, some chose not to agree. All fine with me but I really spent a lot of road time and gas money to figure this out and I hope some find it useful. Here it is:

IN TOWN: Use autostick,start in 1. Roll the throttle medium up to 3000rpm, shift to 2, throttle medium up to 3000 rpm and slap into 4-5 asap and coast or go easy on the throttle depending on traffic. If traffic is moving about 40mph, you should be able to stay in 5th. If traffic slows, let transmission go to 4 as you coast, give a little gas and get into 5th as soon as possible.

HIGHWAY AND INTERSTATE; Use auto stick to appropriately get to 5th. Naturally when merging, you might have to shift into a solid gear or if you are in drive *D*, just merge quickly up to speed. ....
Now you have reached the 'drivers' input. I live in upstate SC but went to Charleston SC (flat) and tried 2 ways of highway driving.

Let's get cruise control out of the way. I think everyone agrees if you use your accelerator and a good coast with minimal 'boost', you get better gas mileage than just leaving it on cruise control. However, one would probably get less speeding tickets if they used speed control.

Now, do I use 5th gear or D (MDS) engaged on the highway??
If you live in the flat lands, with little change in elevation or no hills, MDS does get slightly better highway mileage.
But, when you start climbing elevation or hills with MDS, you can almost hear the gas sucking through the system til it finally shifts into 8 cylinders (5th gear).
So, if you have hills to climb, leave it in 5th and do your throtle with a light foot and you're a good 3-5 mpg better.
So where are my numbers? (on a stack of papers and graphs in front of me). My advice is to spend the 60 bucks for the ecometer which after I calibrated it was very accurate (plugs into the R/T's computer diagnostic connection under the steering wheel). This will help you learn where your shift points should be and how and when to use MDS.
Oh yes, numbers, in town 22-26mpg Highway flat with MDS 24-27mpg, highway flat with 5th (no MDS) 23-28mpg. Highway hills with MDS 21-23mpg, Highway hills with 5th (no MDS) 23-27 mpg.

Now I know some of you are getting better gas mileage but on 4 of my trips I was caught in traffic (2 in city, 2 on interstate) stop and go for at least 15 minutes. So maybe I could get better mileage on a test track with no traffic.
The main point to take from this was the use of the auto stick in town and do NOT depend on MDS to get you the best mileage any where except long stretches of flat road.
Thanks for reading and really hope this can help folks.

Now, I'm gonna go have some real fun and not worry about gas mileage and get some smileage!!!:bigthumb::bigthumb::bigthumb:
 

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Very interesting. Thanks for the post!
 

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Discussion Starter #3
Very interesting. Thanks for the post!
Thank you for hanging in there and reading it. Was pretty hard to condense weeks of calculations, notes, and papers but I hope it wasn't boring. Thank you again and to all who try to help each other!!!
 

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thanks,that is really good to know.i have felt that around town driving left in ''auto''makes the engine lug at low rpms,it just feels better to shift it around 3k and you findings confirms that.here in florida in my area we dont have many hills so i have been using cruise on the interstate.seems like 26mpg was averaged but much lower city driving.i will try to make a habit out of shifting it myself.its fun that way too!
 

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thanks,that is really good to know.i have felt that around town driving left in ''auto''makes the engine lug at low rpms,it just feels better to shift it around 3k and you findings confirms that.here in florida in my area we dont have many hills so i have been using cruise on the interstate.seems like 26mpg was averaged but much lower city driving.i will try to make a habit out of shifting it myself.its fun that way too!
You just brought up a point I noticed but failed to make. Using the auto stick and sensibly reving to around 3000 rpm is a whole lot more fun! Thanks for the input!
 

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Shouldn't the optimum usage of the driveline be something like, point car in general direction, mash throttle, hold on....
 

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Did a 2400 mile trip, in D, used the cruise when I could, 24.9 mpg, town and country. Not bad! Did the same trip in the wifes 2010 Buick LaCross, with the V6, same style of driving, same route, same time of year. 21.3 mpg.
 

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Did a 2400 mile trip, in D, used the cruise when I could, 24.9 mpg, town and country. Not bad! Did the same trip in the wifes 2010 Buick LaCross, with the V6, same style of driving, same route, same time of year. 21.3 mpg.
Very good indeed! Do you have auto? If so, how much of the time did you use MDS? Did you shift any at all? Thanks,, still just trying to grab a handle on this.
 

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I did a test once driving my Charger R/T round trip to Santa Monica from the
Valley. I wanted to see how high I could get the mileage. Some flat, some hills
and getting up and over the foothills twice. I used mds and cruise control. It was
a sixty mile round trip. I was able to average 31.5 mpg. I don't think I would have
done nearly as well without them. Never tested city driving though.
 

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Great info man. Thanks for doing all this research and spending that kind of cash on info for our knowledge base. :)
 

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Discussion Starter #12
I did a test once driving my Charger R/T round trip to Santa Monica from the
Valley. I wanted to see how high I could get the mileage. Some flat, some hills
and getting up and over the foothills twice. I used mds and cruise control. It was
a sixty mile round trip. I was able to average 31.5 mpg. I don't think I would have
done nearly as well without them. Never tested city driving though.
Wow, even on a short trip, that is super gas mileage. My tests did show the MDS sucking in gas trying to keep it in in 4 cylinder mode so I only approached your numbers on very flat roads. Very good mileage - now time for Smileage.
 

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Not to start trouble here but why are we so concerned about mileage in a car that was designed to be a performance car? I wish I could disconnect MDS because when it goes to 4 cylinder mode the throttle response feels like my 1983 Trans Am.

And yes, in California gas is $4.40 for premium and I don't like that but we all know we were buying a car that was going to drink a little bit more. Just a point of view from an older Chally owner.
 

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Despite the considerable weight of these cars, the mpg is surprisingly indifferent to hills (i.e., the trip avg doesn't fall through the floor as you'd expect). As long as you can recoup the energy on the down side of the hill, what you put in on the up side of the hill is well utilized. Ironically, hilly terrain is where you can find the most opportunities to eek out bizarro good mpg, if you are willing to manually pilot the throttle for best effect.

On flat ground, there is nothing to really optimize (unless you are in stop and go traffic on flat ground). So you put the cruise control on, mds engages, and you get the typical hwy rated mpg for the car.
 

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Discussion Starter #15
Not to start trouble here but why are we so concerned about mileage in a car that was designed to be a performance car? I wish I could disconnect MDS because when it goes to 4 cylinder mode the throttle response feels like my 1983 Trans Am.

And yes, in California gas is $4.40 for premium and I don't like that but we all know we were buying a car that was going to drink a little bit more. Just a point of view from an older Chally owner.
No trouble at all but exactly my point - you don't lose a thing (most of the time) with the car in 5th and no MDS. When you're feeling poor throttle response in MDS, gas is sucking.
We both feel the same about this being a performance car, I just wanted to know if we could have a little fun not driving like grandma and not killing the gas mileage. I'm with ya man :thumbsup:
 

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Those mpg readers are a valuable tool for dancing around that tipping point during mds operation. I'm not talking about when it decides to be on or off. I'm talking about that point where it is successfully saving fuel vs sucking fuel. It's such a small change in pedal position as you cruise down a long stretch of road where you may be pulling 24 mpg or you may be pulling 17 mpg. It feels almost the same, and pretty much the meter is the only thing that can tell you for sure...essentially the difference between gaining 1 mph over a hundred feet vs bleeding off 1 mph. Let up just a hair on the pedal, and suddenly mds is delivering another 5-7 mpg! It's definitely worth it, if you are willing to manage that process.
 

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I noticed that during town/city driving my mds never kicks in while in auto mode. The only time it turns on is when cruising on the highway above 70 mph when feathering the throttle. I'm positive about this because its obvious when it kicks in especially with the Flowmasters I have on it. Not that I'm complaining because I'm actually happy it's not too invasive . Id rather it never came on. A friend of mine has a 2008 Charger R/T. I've been in it many times and his mds kicks in at all speeds city and highway. Its very obvious when it does because of the distinct change in exhaust note. Has anyone experienced this also?
 

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I usually drive on suburban roads and MDS can kick in at stable speeds above 45mph. I tend to coast whenever I can.

And to those who have to belabor the point that "these cars aren't bought for efficiency", I say, why not maximize mileage when you can. I don't drive mine like an old grandma, at the same time, I don't find that I have to rev the Hemi at every opportunity and blast my way past everyone else when I know that 1 block down the road I'll have to brake hard for the next red light.

I know I have 370+ HP when I need it, but I don't floor the pedal every time the light goes green. I gain a lot of satisfaction from averaging 22+ mpg from this beast, while realizing that I get a very decent mpg out of a very powerful engine in a very heavy car that has a fantastic exterior. And, I don't keep wearing out my brake pads and replacing rotors.
 

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The MDS in mine kicks in well below 45 mph; somwhere between 35 and 40 mph. I'm showing 23.4 mpg on this tank so far (and my car only has ~2800 miles on it) with a couple of pretty good romps here and there. Wish these cars had an instant MPG reading on the EVIC like my GMC truck had. It was amazing to watch the MPG jump when AFM kicked in.
 
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