my dad has been getting 15 in his new 07 mds hemi 4x4 and it only has a few hundred miles on the clock. like Red said, should get better as it gets broken in. and just for some comparison...15 mpg is what my dad got in his 03 4.7 driving the same route to work and back as hes driving in the hemi.

 

On the highway I have hand calculated results of 15 to 22 mpg on trips, but around town have been as low as 10.1 mpg. For 2006 I averaged 15.7 mpg for the year and so far this year 13.59 mpg. I have tried both regular and mid grade and found no significant differences. I have no upgrades and try to drive reasonably. I have the 20" wheels with the 3.92 gears but am looking at putting on 17's(better selection to choose from)

 

Once you get about 2k-3k miles You will see a huge change. I was worried when I bought it but it gets much better.

 

Just made a 220 mile round trip and got 20.6 with 87 octane, cruise contrl, 800 lbs in the bed and snug top shell. 65 MPH all the way/w some slow traffic, 10 -15 mins.4500 miles on the clock. Its better than when new, the lasttimeat 19.5 and no 800 lbs; earlier, with aprox 3000 miles.
'It probably will get better after my vibration is eliminated!"
Be sure to drive on smooth roads checking for slight driveline vibration felt at 30 to 65 MPH, it comes and goes at diff. speeds!!

 

Just got back from my honeymoon- 400 miles one way. 22mpg going, 13 while i was there 21 on teh way home

 

If you drive with a light foot
and stay at speeds less than 60 mph
MDS can help from 10-20%

If you drive with a heavy foot
drive above 76 mph
install tall, wide, mud tread tires
put on a bug shield
take off your front air dam
etc
then MDS will not help very much at all
(except when going down hill)

see old post below:
----
below is an old post with more info on the subject of
5.7 vs 5.7MDS vs 4.7 vs 5.9
fuel economy
---------------
At least this month (Jan 2007)
Chrysler has been offering the 5.7V8 with MDS as a
"no cost upgrade"
over the 4.7 on Rams
and pointing out to customers that
the 5.7MDS has better EPA MPG test results by about 1.
When evaluating this, keep in mind that you are comparing a 5.7V8 running on 4
cylinders (and dragging along 4 not being used) at a speed of 55 mph to a
4.7V8 running on eight cylinders also at a speed of 55 mph.

At speeds of 70-79 mph the MDS on the 5.7 Ram will not kick in unless you are
going downhill, or have a wind at your back. Here at higher speeds the 4.7
might regain an MPG edge.

Even before MDS was introduced on the 5.7V8
the unmodified EPA lab results were showing
that the 5.7 was within 4% of the 4.7 V8
in fuel efficiency.
The actual test results are available online from the EPA at:

http://www.epa.gov/fueleconomy/data.htm

to see the actual results go to this link:

http://www.epa.gov/otaq/tcldata.htm

These are not the 'Window Sticker' numbers,
these databases have the actual city and highway test results down to a tenth
of a mpg. This makes it easier to compare. Since 1985 EPA has applied a
'fudge factor' to these actual results to get the number that you see on the
Window Sticker. This happened because citizens complained the EPA city and
highway numbers were TOO HIGH compared to 'normal driving'. Next year EPA
will apply an even greater 'fudge factor' because citizens are still
complaining that they can't get at 79 mph the MPG that EPA measures at 55 mph.


If you look at the 2003 year numbers
you can compare the Magnum
5.9V8 to the 5.7V8 (without MDS back then)
and to the 4.7V8 and 3.7V6

3.7V6 2wd had 25.4 MPG highway with 45RFE and 3.55 diff
4.7V8 2wd had 24.2 MPG highway with 45RFE and 3.55 diff
5.7V8 2wd had 23.3 MPG highway with 545RFE and 3.55 diff
5.9V8 2wd had 22.0 MPG highway with 47RE and 3.55 diff

Chrysler's official press release on the 5.7 Hemi said that it was 8-12% more
fuel efficient than the 10 year old Magnum 5.9V8 design. But notice
in the above that in the 2003 Ram pickup the 5.7 Hemi was only (23.3/22) 6%
more efficient at highway speed. This may be because the 545 automatic
transmission has more internal friction when in overdrive (where it has two
planetary gearsets turning) compared to the older 47RE auto that only had one
planetary gearset turning.

For comparing the 5.7 with MDS to the 4.7
look at the 2007 year numbers.

4.7V8 2wd had 23.7 MPG highway with 545RFE and 3.55 diff
5.7MDS 2wd had 25.4 MPG highway with 545RFE and 3.55 diff

Adding MDS to the 5.7V8 at a steady 55 mph improved it by
(25.4/23.3) or 9%
This matches what Chrysler said in their press release about MDS on the 5.7V8
where they wrote the most gains were below 60 mph, with maximum gain of 20%
around 45 mph.

2wd 5.7 Rams will be able to go a little faster in MDS mode and get better MPG
than 4wd Rams because the extra driveline friction and weight of the front
axle loads the engine down more.

 

I've been averaging 21-22 on the hwy at 65-70 and 16 in the city. So yes, the MDS works as long as you keep your foot out of it and just drive normally.

 

If Dodge has any brains at all, they have the MDS programmed to not activate at all until the engine is broken in. i.e. has more than a few thousand miles on the ODO.

 

I see your point JRH. I'd have never thought of that.