I posted on another thread that the best MPG I had ever gotten was 17 MPG. Well, 3 days ago I installed a tonneau cover and today I headed out to one of my metal detecting places, (128 miles round trip). When I left the house I hit the reset button on the overhead display. As soon as I left the city I set the cruise at 65 MPH. Slowly my mileage ticked up to 19.3 MPG. On the return trip, (a very slight downhill) it slowly ticked up to 21.3 MPG. Is it possible that a tonneauu cover could help that much???? If I read my manual correctly, it's best to hit the reset button on the overhead display every so often as the display becomes less sensitive over time, (Pg. 119). Is there any other way to make sure the display is correct? Who knows how close it actually is.

 

Check it the old fashioned way

1) Fill up truck
2) Drive
3) Fill up truck
4) Divide miles driven by gallons used
5) This is miles per gallon.

 

It makes a 1 mpg difference at best.

 

should improve between 5 - 10 % of what you were getting

 

You should reset display on fillups, not between. That will give the average of the tank. If you want the average of the trip, then reset before you go.
I agree with Frenchy. Old fashion way is the best, unless you use a station that cheats you.

 

I hit the reset button when I left the house the morning after I had filled up the night before. Tomorrow morning I'm leaving on a 400 mile, (round trip) Javelina hunt and will use the, "old fashioned way" as Frenchy suggested. I know what the display read but, I myself don't really believe it, we'll see.

 

Well I did what Frenchy suggested to check my mileage. We drove mostly at about 70 miles per hour sometimes 65. Stopped 255 miles later and filled her up. According to my math (?) I was getting 18.3 MPG. Meanwhile the overhead display was reading, 20.1. So I guess the tonneau cover was good for almost 1 1/2 MPG increase. Can't complain about that.

 

A year or so ago, Mythbusters did a thing about gas mileage on one of their shows. Part of it had to do with 'drafting', and another aspect involved a pickup truck with and without a bed cover. Their results supposedly proved that mileage doesn't increase with a bed cover. I've always called BS on that since I've had trucks both with and without bed covers and ALWAYS got better mileage when a cover was installed. It wasn't much, maybe 1/2 - 1 1/2 MPG depending on driving conditions, but I never understood that. First, how they could get those results. And second, how they could report no improvement and just have people blindly follow their findings. :/