Hey guys,

I recently took a trip in the truck totaling about 750 kms. On the first half of the trip I just had passengers with a fairly gusty head wind. On the return I had the same passengers plus a load of firewood. Not sure about the weight but I had the pan completely full and she was squatting right down to the rubbers (pretty sure it was over 1000#). When I drove with the load I put her in Tow/Haul mode and actually made slightly better mpg hauling than when I drove out empty! I must say the truck rode beautifully with the added weight and I was expecting poor throttle response and poor mpg. I was pleasantly surprised that the truck could get decent mileage and pulled like a train - and we have some of the most hilly terrain here on the east coast.

I also noted while driving out empty that if I drove the truck in manual mode instead of MDS I actually got a little better mpg. I credit this to the truck not slowing down while coasting with the MDS on.

So basically I am puzzled about why my truck gets better mpg when hauling in tow/haul mode and with the MDS disabled during normal highway driving. Shouldn't the MDS improve mpg - not reduce it?

By the way my truck has the 3:92 gearing with 20" wheels and my city/hwy mpg does not vary very much - maybe +1 mpg hwy.

Just wondering if anybody has had similar experiences?

 

Tow/haul changes the transmisson shifting. Locks up the converter earlier in more gears thus reducing the rpm's. Alot of people actually agree's that turning MDS off with a tuner gets better mpg. During "ideal" conditions, MDS "can" net some pretty amazing results. But how often are we actually driving during "ideal" conditions?

 

My experiences are the opposite. I get much better MPGs with the MDS on, towing or not. The biggest impact to my MPGs is the wind. Tailwinds with MDS is the best, headwinds with MDS basically eliminates the MDS. When I tow from the coast of California to Arizona, I get good tail winds from the ocean across the deserts. I basically leave the TOW/HAUL off and can tow my trailer in OD and MDS on the downhills and can get 12 MPG, on the way back with the headwinds, I put TOW/HAUL on and get about 9.5-10 MPG.

 

Yeah two things that we have here in Newfoundland that aren't good for mpg is wind (typically no less than 15 km/hr on a calm day) and hills. If i'm just cruising around the outskirts of town and keeping it under 80 kph I think the MDS helps some, otherwise not so much. I currently am getting around 15 mpg on my daily commute (rural roads some stop and go and city) and marginally higher (say up to 16 mpg) highway. I am hoping this will get better when the truck breaks in (only 5500 km so far) but I am happy since my old 2003 ram couldn't seem to get better than 12-13mpg and occasionally up to 16 hwy. I think a major reason for this is the rear end - my old 2003 just had the 3:55 and it loved gas no matter how much i babied it. The 2012 is much gentler on the pocket book

 

Around town and for that matter anytime I drive below 50 I am always in "5"(I manually shift it into 5). I usually get about 14-16 around town. On the highway I use the MDS with the cruise control and on the straight and flat highway I can get about 21-22. I also have the 3.92's. I have found with a headwind you just kinda get what you get---depending on load and speed.
Jay

 

I've certainly noticed that the truck drives a lot better in tow/haul mode. I've also noticed that in normal driving conditions, with cruise control on, the mds/eco mode sucks. I set cruise control at 65 mph. As long as the road has a slight downhill, it will stay in eco mode forever, getting pretty good gas mileage. However, as soon as it flattens out, the eco mode will struggle and the truck will slow down to 62 or so, then eco will turn off and the truck will accelerate up over 65, usually to 67 or 68, then back off a bit. Eco mode will come back on, but of course, since I'm not on a downhill anymore, it will slowly lose speed until it's back down to 62, then the eco mode will turn off, and the cycle will repeat. I think going from 62 to 68, back to 62, back up to 68, over and over nets worse gas mileage than just leaving eco off (either truck in tow/haul mode or gear selector set to 6 instead of drive). With it in 6, the cruise control still isn't perfect, but in tow/haul mode the cruise control works perfectly and only varies a mile or two per hour and only during elevation changes. It certainly settles back to the set speed much more quickly and doesn't under/overshoot as extremely.

I decided to leave eco off (manually select "6" every time I start the truck) for a few tanks of gas to see if mileage changes at all, but I keep forgetting.

[update: Oh, I have a 2012, 2700 miles, 3.92 gears, crew cab hemi.]

 

The wind was your biggest problem. I am one of those who loves MDS, only on the highway tho. When I am in town I use the manual shifting to keep the rpms at a good level, not to mention its a little easier on the braking from the engine braking.

The problem with the MDS, is it does not factor in the wind. MDS is based on the throttle percentage, speed, and power (probably more then that too). MDS disengages at a certain throttle level, it will not turn on over a certain speed (unless downhill) and once you are over a certain HP level it will not turn on. Its many factors that affect it, but it cannot account for the wind. The wind effects the truck in too many ways, direction and speed. Your not always pointed in the exact same heading and the wind is never blowing at the exact same speed! Because the MDS is always constantly engaging and disengaging and the truck doesnt know what to do.

I put mine into manual in the wind as well...

 

The way I drive my truck is in MDS I bet at least 75% or more most of the time.

 

Lots of opinions on what works best which is great. Don't get me wrong I think MDS does increase mpgs - especially while cruising on fairly level roads. Its not nearly as annoying as some on this site would argue, but then again I don't have an aftermarket exhaust or anything. I'll definitely try using cruise while in Tow/Haul mode to see what I get - usually I can't stand cruise because of the downshifts in hilly terrain. On a side note, do any of you guys find that the manual shift isn't very quick to respond? I find it will readily downshift but won't upshift until it is damn good and ready!

Glenn

 

In the real world with the way most people drive mds is pretty much worthlesss IMO. There are rare instances where it does work but they are rare indeed. If you drive 65 mph on straight level ground with little to no wind then it can help. But 95% of the time for me it is just a nuisance. This was not one of Dodge's better ideas IMO. I don't understand why they didn't set it up to where the owner could turn the thing off if they wanted to.