Ok, so I took my HEMI on it's first long road trip. When I left I had 16k on the truck, now there is 18k -- 2000 miles round trip, FLA and back. Not only did I get a tan but I discovered how to effectively drive my truck to get the best miles per gallon. After I got on Rte. 95 South (driving at night straight thru) I set the cruise control on 69 mph. I reset my overhead computer and averaged 19.5 miles per gallon for about 200 miles. I wanted to quicken the pace so I raised the cruise to 72 mph andI watched as my mpg dropped to 18.5. I then decided to bump the cruise to 80 mph and after about 100 miles I was averaging 16.5 mpg. So, for all of you guys who whine that you get terrible gas mileage on the highway, you're doing or not doing one of two things. You're either not resetting your overhead to calculate only highway miles or you'restomping on itevery time you see a Tundra. Lesson?

69 mph HWY = 19.5 mpg

Peace

 

I will have to try that today and see how mine does. The only time I have been on a long road trip was with a cargo trailer in tow to Mississippi but I still got 10 mpg with the 16 foot tail wanging. I'm going to Nashville so I'll check it out. Thanks for the test!

 

Good to know, 19.5 mpg is great. I can get near 16 in my PW on level ground with the wind blowing im my favor . Otherwise, I get over 15 on long trips.

 

19.5 without MDS ... that's good.

 

I applaud morganmkelly for posting those MPG vs mph tests on I-95 southbound.

Every Ram owner can learn a lot from doing tests like that,
and it is a good way to keep from being bored
after too much listening to the radio.

It also looks like your Extang tonneau might be helping your truck's aerodynamics, if you were using it during your trip.

I can get
19.5 MPG at 69 mph
18.53 MPG at 72 mph
15.94 MPG at 80 mph
as estimations in the Fuel Economy Calculator Program
if I improve the aerodynamic 'goodness' number called Cd
from the factory stock 3rd Gen Rams
Cd=0.528 (open bed without a tonneau)
to a better Cd=0.485 with a tonneau.

That is about a 8.2% improvement
and similar to what others have found when a tonneau is put on the bed.

A stock 3rd Gen Ram would get lower MPG numbers at the same speeds,
something like:
18.6 MPG at 69 mph
17.6 MPG at 72 mph
14.5 MPG at 80 mph

A 2007 Toyota Tundra claims to have a
Cd=0.37 for 2wd and 0.38 for 4x4
and many of the improvments appear to be making the underside of the pickup that you don't normally see less turbulent to the air.

If the Ram body were to be improved to Cd=0.37
the fuel economy on strictly highway cruise would improve to:
22.2 MPG at 69 mph
21.3 MPG at 72
19.0 MPG at 80 mph

All of these numbers can be affected quite a bit by head, tail and sidewinds
and the estimates above are with zero wind.
Tires also can affect MPG and i used a rolling resistance of 1% which is approximate for 'pretty good' highway tires that have worn away part of the tread depth. Some "mudder tread" tires have rolling resistances of 3%

 

Where is the fire you are going to that needs you to go 80? Hell even 72?

 

Depending on where he was on 95, the speed limitmay have been70 (Mostly through the southern states such as the Carolinas and Georgia). In reality in CT, if you are doing 65 on I95 you are going to cause a wreck. I have a lot of friends in both local and state police depts and they won't bother to run you down unless you are going over 80. And 75 is the average "normal flow of traffic" speed in these parts.

 

I've reset the computer and set the cruise to 100 km/h. If I recall, I achcheived about 22 mpg.

 

Ya think this scientific method will help when Im towing the 5k lb travel trailer ?

 

Last week, I went from Albany,NY to Myrtle Beach,SC. Pulled 5000 lbs. travel trailer both ways. On the way down, I used Cruise and tow haul mode, got 8.6 mpg. Going home, I used my foot and no T/H mode (to force MDS to work) and got 15.9 mpg. I ran between 70 and 75 both ways whenever possible. With or without the trailer, my MDS doesn't seem to come on nearly as much with cruise engaged.