18.5 MPG on an 800 mile trip after years and lots of bucks spent unsuccessfully trying to increase my highway mpg from 12 - 14.

Cost me $299 which is the cost of my Garmin i3 trip navigator. Using this tool, I found that my speedo was way off. At 65 mph I was actually traveling at 72 mph. I kept the speedo at 59 the whole trip (65 mph on the i3) and finally got decent MPG.

Seems that 65 mph is an optimum speed for mpg and speed.

Great excuse for purchasing a GPS navigation tool.

aloha,

ihilani

 

Yea, you nailed it with the best way to save fuel with these trucks. No mod works better than just backing off of the pedal.

All Fords come with a speed o meter that is off by at least 2 mph. All of my vehicles were off the same amount. I think Ford does it on purpose to give us the impression the fuel mileage is better than what it really is. 65 is really 63.

You must have larger tires that caused the difference in yours. Just think, when you thought you were doing 75, you were doing 82. That's when my truck really drops in fuel mileage. At a true 65-70, I can get 17-18 mpg. Over 75 and the mileage drops like a ton of bricks.

At 85 and I'm lucky to get 14-15.

As much as I like the higher highway speeds, 75 in Arizona, 80 someplaces in Texas, I realize the difference in fuel usage and the amount of fuel wasted. I wouldn't vote for it, but I wouldn't be upset if the National limit went back to 65. 55 was just to slow. Regardless of the vehicle.

 

What kind of trucks are you driving? 4x4's? Screws? size of tires?

 

if i draft with my lifted 4x4 i can get 19 lol

 

Hello all,

Sorry about the lack of details, my truck is a 97 4x4 4.6l, 5spd manual.

I replaced everything a person can replace on the f150 at home with the hopes of achieving the 18-20 mpg that I've seen a few people claim on this forum. I also read a newspaper story about for big SUV's they did a calculation to determine the best balance of speed versus economy and they found that due to the large frontal area and related wind resistance, there was a huge loss in efficiency moving from 65 mph to 75 mph. At $2.50 per gallon, the extra 4 mpg saved me $32.

I'm not patient enough to try the same trip at 60mph.

 

I drove down to Virginia last winter, 12 hr road trip. From highway gas station to highway gas station I got 21.4 mpg. 1998 2wd 4.6L w/ a k&n drop in. Stock other than that. I have never gotten that mileage before and never have since. Only difference about that trip was I was following my grandmother down and she is one of thoes drivers who speeds up and slows down. So cruise control was a waste of time and I just used my foot to match her speed (which varried from 65-85mph). I almost always use cruise on a trip like that. Think not using the cruise control could increase mileage?

 

I think it hurts mileage on hilly roads. Without cruise, I will let the vehicle slow going uphill, and increase speed a bit down hill and it seems to increase the mileage. The cruise control really makes it downshift alot on steeper grades.

 

I like mods that increase MPG while I'm driving hard because.........that's how I drive.......LOL and I am happy with that.

 

Just got back from a 440 mile trip. I kept the cruise on at 72 and got 17.4 MPG.

 

um...yeah I have 12.8 mpg according to my edge. I do drive like an idiot though (on-off-on-off throttle) I guess it is just that I am never home...when I am I gotta let off steam in a couple of ways, driving being one of them. As an example today I was driving when a mini-cooper blew by me doing 63 in a 45. at the light up ahead I just had to beat him...It's in my blood I think cuz my dad has bad speeding tickets and when we lived in Europe the Autobahn was his friend but well...yes my mom's 5.4 ltr. gets 4 better because she drives like an old lady

 

guess I am going to have to learn to drive. I average 13.7 in town and the BEST I have ever gotten was 16.8 and that was on a 382 mile trip between fuel stops with a constant 20 to 25 mile tail wind. I have 42,000 miles on my 05 screw 4x4 with 3:55 gears, it does get about 3 mpg better now that the weak injectors have been replaced, the first 35,000 I was lucky to get 14 on the hiway and around 10 in town. but they aint built for economy and that is not why I bought it.

 

Saturday I took a drive. There was no need to be in a hurry, I took country roads and leisurly wound my way around a 200 miles voyge in Eastern Ky. Much of the trip was at 50 MPH or less. Road conditions were such that I did not seem to be holding up traffic. A time or two idiots had to cross double yellow lines to pass me, on their way to what? I was miles from any major town. Seems to be a habit with some people. When I got back near home I topped off the tank again. Took 14 Gal. and I drove 201 miles !! This is 14.35 MPG. Not too good you say? Well my truck is a 96 F250 with a 7.5L (460) and a 4:10 rear axle!!!!!! It can pull about anything I hook on to. The mileage is usually around 10/11 MPG solo and even a steady 10 when pulling a 5000lb low profile 5th wheel. The 460 is considered a gas hog by most folks. Torque numbers at 2000 RPM make it a superb tow engine!
I found out years ago that speed equates to MPG. I have gotten over 15 MPG on this truck once before.

As the government requires the major auto companies to get a higher over all MPG average for their models (CAFE rules) it seems to me they are overlooking a quick cheap fix that requires no technology lag or painful re engineering or downsizing. SLOW DOWN! Think of the immediate gains in MPG and the benefits of lower insurance that would come from fewer accidents!!!!! I'm not saying everyone drive 50. I'm suggesting that lower the national max limit to 60 (that's one mile per minute) but most importantly........E N F O R C E slower speeds. Most people now travel the interstates at 75/85 even though the posted speed may be 65. Rarely do we see Highway Patrol in West Virginia.

Also, I have checked my speed and odometer with mile marker signs on the interstate. If I set the cruise on exactly 60 and the trip odometer on zero, the mile marker signs click off exactly at one per minute and at the end of a long run, say 30 miles, the trip odometer is exactly at 30. This tells me my speedometer is reasonably accurate.

 

i finally hit 15... had to let my truck idle and get up to operating temp first. before driving it. if not it stayed in cold range the entire time. damn this "global warming"!! lol its to damn cold in texas now.

 

I found it very amusing this past wekeend to see the computer giving me 17, 18, 19, and finally 19.6 MPG on a trip home from the mountains. Just in case anyone takes me seriously, I must qualify the above by stating that I was at 4000' and made a nice long, gradual coast (no one on the road) down to 1400'. No, I do not think that is my actual mileage; but amusing to me.

Most of the time, I am at 13.5.

 

Ihilani,

After you determined your correct speed with the GPS, it appears that your speedo was reading roughly 10% low. When you calulated your mileage on the 800 mile trip, did you also factor in that your odometer was probably roughly 10% low, too? In other words, if your odometer said you went 800 miles, you might have actually gone roughly 880 miles. Your gas mileage might actually be around 10% better than you thought it was.