I was curious to see what type of mileage potential I could get from my truck if I was to slow down. We were headed from west Texas to LA which I was estimating to be over 700 miles one way.

Here are the quick specs on my truck for the trip:
2011 F350 6.7 CC FX4 LB 3.55 18" Lariat wheels/stock Michelin tires, 80 psi rear, 70 psi front, family of 4, lots of luggage, 2 strollers, ice chest, tools, etc...

On the way to LA on a full tank with the cruise set at 60 mph: just over 23 MPG! Wow...I made it to LA in one tank for a total of 726 miles and still showing 75 miles to empty


http://i1086.photobucket.com/albums/...0/DSCN2978.jpg

http://i1086.photobucket.com/albums/...0/DSCN2981.jpg

Check out the new miles to empty after my first fill up: 867 MTE

Drove around LA for almost a week and remained in the 20 range.
Drove to Las Vegas then back home to west Texas. On the way back I upped the speed to 70 MPH and averaged 19.7 MPG. Being used to the 23 MPG, I decided to slow it down to 65 MPH and mileage went up to 21.7 MPG so I was happy. The gallons used displayed on the dash was mostly accurate off by about 1/2 to 3/4 gallon per tank.

I think if I would have taken it down lower say, 55 MPH, the mileage could have gotten close to 25 MPG which is amazing for a truck like this. I didn't really mind driving slow at 60 MPH, it was a direct drive with only road side rest stops used. BTW, RPMs were just under 1500 going 60.

P.S.-Sorry for the photobucket link, still havent figured out how to do a direct paste.

 

just bracket the url with [img]..[/img]

 

 

Here it is:

 

Thats not fair.

The best I saw was about 18.3 on my way out on my recent trip (about 2200 miles). The way back I was around 17.5. When I got home I was averaging about 15.5 for some reason. Now I am back up to about 17. Not sure what the deal is there. I've never seen 20, I have seen in the 19 range but once a regen kicks in it goes back down.

I do have a tonneu cover and a bit of weight in the truck so maybe that drops it.

 

As we know temps and terrain play into this. Traffic,etc. Also if A/C's on it will pull down MPG. It doesn't take much to drop it a few mpg. On my runs from NH to Ma going thru Boston with speeds of 72 mph I average 18.5 or less. On rural roads with no traffic averageing 55 I can get a little more. Maybe 19 or 20 if I"m lucky. But that's rare.

 

I did 19 round trip to Tenn and I was doing 5 over the whole way with air. I think I did good and love my truck...

 

Having seen the fuel prices in LA recently, all I can say is that even though you had enough fuel to make the full trip, you should have topped off before you crossed the border into Kali.

Good test and report. Thanks.


Joe

 

Great info, this lends credibility to the argument that slower speeds mean greater efficiency!

 

That would most certainly be true. Wind resistance increases at the square of the speed = more HP needed to move the faster you go, not just faster RPM's.

Something I started working on is an extension to my air dam. The more you can deflect the air around the bottom of your vehicle (and around the wheels) the less resistance you'll have = less HP needed. If you have paid attention to semi trucks recently, in the past couple years, more and more box trailers have the "fins" on the bottom side - they start out behind the landing gear inside the frame and extend the length of the trailer back to the rear axles, on the outside, to deflect air from underneath the trailer. I would be curious to see some numbers to show the performance of these. I am sure the same concept can be adopted to a pickup truck.

 

Of course you're completely correct here, Steve. I grew tired of trying to make that argument after so many people came on to refute this, as most don't like justifying going slow. Data like this is tough to argue though!

 

I just put 1700 miles on my 2011 Job 2 F350 PS (round trip North Texas to NW Kansas). With this engine I discovered that your fuel's Cetane number makes a big difference in mileage. On a whim I dumped ~20 oz of Diesel Kleen into the tank before departure, that got me 18.6 MPG @ 75 mph with AC. Second tank, no Diesel Kleen but everything else the same, dropped me to 16.5 MPG.Third and four tanks got me the mid 16s as well.

Semi-aside: On trip up outdoor temp ran between 105 and 112. Trip back exterior temp topped out at 115 in North Oklahoma. Lots of cars/SUVs on the side of road with overheated engines and blown tires. Truck did not mind the temp at all. When will people learn about proper maintenance and regular inspection...

Steve

 

The terrain on my trip was mixed. East of Tucson there are some steep hills for long stretches. After Phoenix was mainly flat. I had the AC on the entire time. I am very happy with the mileage.

 

While I was driving South on I-95 through Jacksonville, FL I saw what looked to be a pre-2000 year model SD with a low front valance made out of what looked to be like sheet aluminum. It was going Northbound so I did not have a chance to take pics but I thought of you immediately. It didn't look great but the shape and rigidity looked good.

 

So there ARE other wacko's out there! Oh wait, maybe I shouldn't say that.

Though, I would be curious if anyone has done this and had some data to back it up. I used some hard rubber molding strips to make mine but they are too flimsy. I didn't trust them being on there so I never hit the road with the assembly. I will have to make something else.