I just purchased a A.R.E. Lid Top for my truck and it seems that my MPG is going down. I averaged between 13.5-14 mpg driving to work Monday - Friday (about 15 miles total per day). Now, with the lid I am getting 12.5 mpg driving about 65mph. I tried turning off the AC and opening the windows and that didn't do much, only about 1-2mpg better. The lid only weighs about 90lbs. Is this because of the lid or something else? My tire pressure I check regularly and alway change my oil at the correct miles.

Thanks
Brian

 

It is not like the old days where driving with your tailgate down or putting a cover on will improve your mileage. you've changed the aerodynamics; these days it's unlikely to do that and get a positive result.

 

I have the same lid on my truck and I noticed about a 1-1.5 mpg increase. Maybe you picked up some less than good quality fuel, that happens sometimes.

Greg

 

Trucks are now designed in windtunnels just like cars. Adding a bed cover won't always give positive MPG gains. There is a "bubble" of air the circulates within the bed of the truck at highway speeds which prevents normal airflow from affecting the dynamics. Try putting a small branch with leaves in the bed of the truck and then drive down the highway, you'll see this "bubble" I'm speaking of. The branch will eventually blow out due to cross winds and other turbulance the windtunnel cannot simulate.

 

I got a ARE cover put on and I did noticed a considerable increase in gas milage.

 

I'm not sure this will add anything to the thread but perhaps someone will educate me about calculated MPGs

I was getting 13.5-14 MPG for a long time. Then, out of curiosity, I was playing with the switches on the steering wheel. Clicking on the RIGHT ARROW switch while my indicator light was on MPG took me to a new screen which had an option to recalculate my MPG. So I clicked YES an my MPG immediately popped up to 18-19. Zowie! Meanwhile, since I was on a trip from San Francisco to Salt Lake City, my round trip actual MPG via the gas pump was 18.6.

At one point, coming downhill, my MPG hit >30. Of course it didn't stay there but much of the trip was >20.

So there you have it. Can anyone explain what's happening?

 

First - only real way to calculate mpg is to start with a full tank, drive and note the milage when you fill up again, then do the math (miles/gal used). The mpg indicator in the evic can be off by +- couple of mpg.

I believe when you reset your mpg, it starts (not at 0) but at what you were at at the time of the reset. I know when I reset driving on the highway, it climbs up in mpg. Going down hill at highway speed the mds kicks in to 4 cylinders. You would have to maintain downhill and that speed to actual get the high mpg indicated. That is why you will see it go down in mpg very fast when pulling long grades.

I would hand calc to see what you are actually experiencing. My Ram mpg indicator seems to be off by 1.5 to 2mpg on the high side. It may read 18 mpg when in fact, I'm getting 16.5 mpg.

 

I always reset my MPG computer at fill up (and before I drive off), and check it by hand calculating. Usually its pretty close, partially computer inaccuracies, partially pump inaccuracies (say one pump shuts off later than the one you used last time, thus filling the tank higher than previous).

I drive 90% highway 10% street, and I get ~19mpg (hand calculated) +/- 1mpg.
4x4 crew cab w/ 3.55 gears, 5500 total miles on the truck.