I used to drive 65-70 mph on the highway and I would get 19 - 20 mpg. When I was towing I would get 10.5 - 11 mpg.

Now...I have slowed down to 60 mph on the highway and I am getting just over 21 mpg. When I am towing, I am getting about 13 mpg.

Hand calculated. Not DIC numbers.

I love this DuraMax! I never had such a great truck!:D

The very few times that I drove those speeds I got very similar MPG. And I drove at level 4.

Absolutely--It is all in the AERO!


Our trucks can literally be barn doors going down a freeway. Takes lots of power and fuel to push it over 65.

Slowing down --just a bit--produces dramatic fuel mileage improvements

we consistently get much the same degree of improvements in fuel mileage with our 3500 with our Hot Juice on the 60 hp setting .... we've also found as long as we keep the speed at or just above 60 mph our truck to take hills in OD that she'll downshift to take at 55 mph

Jim

Basically, you are saving a couple of gallons per fill up so figure you are saving around $5 a tank by slowing down...

I'd rather spend the money and go faster. My truck seems to be most happy running between 70 and 75 and that is usually where I run on the highway, traffic permitting. Besides, I'm in SoCal, if I did 60 I'd get run off the road. The speed limit on the freeway near my house I live is 70!

Also seems a shame to waste all that power, especially with the edge...

My LB7 gets the best mileage at 60-62mph. Usually 21-22mpg. I have read other owners say the same thing...very tight range for best mileage.
But I only drive that way when traffic is a moderate..everyone passes me.

Late at night, when the freeway opens up---I cannot help it...cruise control at 80mph...

I did some tinkering a couple weeks in a row.. I drove my truck (LB7) the 25 miles to work and 25 miles home...less than a mile to get on the freeway both ways, let idle for exactly 3 minutes before leaving. I didn't drive it to the store or anything in those weeks...only to work.

1st week- With 295's and green keys leveling it I got an average of 20MPG cruise set at 60 one big hill mostly level.

2nd week -With 295's and TBars lowered as far as I could (almost stock height) cruise set at 60 I gained an average 3 mpg

Aero push has alot to do with the fuel economy.....little 245's and wedge shape could raise it a good bit I suspect?

:grd:

My .02

I did some tinkering a couple weeks in a row.. I drove my truck (LB7) the 25 miles to work and 25 miles home...less than a mile to get on the freeway both ways, let idle for exactly 3 minutes before leaving. I didn't drive it to the store or anything in those weeks...only to work.

1st week- With 295's and green keys leveling it I got an average of 20MPG cruise set at 60 one big hill mostly level.

2nd week -With 295's and TBars lowered as far as I could (almost stock height) cruise set at 60 I gained an average 3 mpg

Aero push has alot to do with the fuel economy.....little 245's and wedge shape could raise it a good bit I suspect?

:grd:

My .02
I know what this is about. From bone stock, to 6" lift with 315's and the T-bars up, I lost almost 12mpg. Now that's Canadian mpg, not American, but it's still quite a bit!!!

who in the heck wants to drive 60 on the hwy

Pretty difficult to stay at 60-65 when you are traveling in areas where the interstates are not crowded (ie San Antonio to El Paso and such) or on some Nevada state highways. These are places where you can travel 75 and average about the same. When the roads crowd up and you try traveling 75 as much as possible, you'll probably pass the same guy who's steady on at 60 a bunch of times and you'll really be pushing fuel to the engine with all the speed variations you go thru. This is when you need to clear the ants out of your pants and settle down and stay with the traffic flow. You'll make just as good time and keep a few extra gallons in the tank.

its gonna be a challenge..my last time out i told the wife..she just found her sweet spot...she loves to pull at 70..was hard for me to believe..

Typically in S.E. Montana the interstates are uncrowded so that the 75 mph speed limit is usually about 5 mph below traffic flow. Some folks are traveling slower these days around here, myself included. Dropping my cruise speed of 79 to 72 mph gets me 3 to 5 mpg. At 72 mph in favorable conditions, I'm calculating about 20 to 21 mpg. Yeah, my t-bars are cranked to level the pickup and I'm running 33's so there's a few factors to consider. I use a gps to calculate my actual highway/trip miles instead of relying on the speedo/trip meters. All in all, not to bad. I don't think I could bear to travel out here any slower than this, though.

BB

RV FULLTIMER, SLOWING DOWN IS GREAT FOR MILEAGE, BUT IT SUCKS FOR ALL THOSE BULLET HOLES, FROM THE PEOPLE BEHIND YOU, THAT YOU'RE PI$$ING OFF!http://www.dieselplace.com/forum/images/smilies/eek.gif


BTW SLOWING DOWN HELPS ON THE UNDERWARE IF YOU'RE IN FOGGY CURVY COUNTRY!
http://www.dieselplace.com/forum/images/smilies/lol.gif
Doug

all i ask if your going to drive that slow,PLEASE stay the hell out of my way.....thank you....:D :D