I do mostly city driving. I have a lariat with the onboard computer which displays fuel economy. I do not have very much faith in it's accuracy. I have been playing around with overdrive, and without. I drive the same route everyday from work and there are not much for traffic variables because I drive at night when there is little traffic. The computer shows 12.80 (+/-) mpg while driving the same route daily while in overdrive. I noticed that my freeway mileage gets better at higher rpm say 65-70 mph vs 55-60. I have noticed that turning off the overdrive in the city increases my mileage to 14.70. Like I said, I don't know if the computer is very accurate, but it does recognize a improvement.

 

How is that possible?
More RPM's = More Fuel delivered to the engine...

 

I see multiple views, but no votes. I think most people probably don't do these experiments. They leave OD on unless they tow something or are on a steep hill. But tell you what. I turned OD off today coming from work. I'll leave it off one week with my normal driving to see what happens. I've averaged 14.8 to 15.0 MPG. I'm a reletively conservative driver on the outskirts of my city. I do some weekend cruising in town, so maybe that will factor in. If I see a significant difference after one week, I'll find this thread and report it.

 

I haven't done this experiment yet either, but will give it a shot. I do mostly highway driving, but I will try this when I'm driving in the city or in stop and go traffic on the highway and will post my results as well.

 

Interesting... I'll try it too.

 

I'll try it too....anything to improve gas mileage WITHOUT increasing costs!!!

 

You'd think that if this is true that Ford would advise of it.

 

It doesn't hurt to give it a shot. Maybe OD is better for highway driving only and stop and go really does give better MPG. People may have drifted to always just keeping OD on. It seemed to work for Triton.

 

I'm going to try it. I drive maybe 15 miles on an average day and half of that on rutted dirt roads. It never occured to me to shut off the overdrive. I've got 1000 miles on the truck and I'm getting 13.8 mpg.

 

Having overdrive on will give you the best mileage, at least from my experience, unless of course the truck is hunting between gears. In my truck it kicks into overdrive at around 40-45 so as long as you're running steady at that speed you should get the best mileage. I only turn overdrive off in the city if the traffic is stop-and-go or if i'm going under 40 for a long time. I also heard on a car show that Chevy trucks supposedly get their best mileage at between 40 and 45 mph, which is most likely the minimum speed those trucks can be in overdrive. So ford's shouldn't be much different.

 

in overdrive it takes more pedal to excellorate that might be reason for the better milage on the gauge

 

cant say on the 04 cuz mine hasnt come in yet but my 99 got better fuel economy leaving it in overdrive but my 00 vette got much better mileage in the city leaving it in drive, possibly the gearing.

 

It seems nearly impossible to get better milage without overdrive than with. Simply a basic gearing issue.

 

Why is it that the truck does better at higher RPM. I know that the best freeway economy is at 65-70 mph as opposed to our local limits of 60mph.
IMO it stands to reason that higher rpm in the city may be a bit more efficient too.

I cant provide a full report yet, but when I am satisfied with results from further
goofing around I will post my findings.

I think Toreador is doing the same.

 

The answer is kind of obvious. At 40 mph, you run slightly less rpm than at 60 mph. So your fuel/time ratio would be larger. However, at 60 mph your distance/time is greater than at 40 mph. So if you divide (distance/time) by the (fuel/time) you get distance/fuel which is mpg. The best mpg occurs when those two values produce the largest mpg value.