chipmonk

had a 2nd gen, that said i was getting 30 mpg! i refuse to let anyone tell me that it was wrong, because it made me feel great, just seeing it up there every day!

Hintz

Had a 6.0L 03 GMC that said it got 12.5 MPG and hand calc was in the 14's , go figure you'd think the man. would make them high so people feel better about buying gas guzzlers

0524VHO

my overhead stays around 22 and im actually gettin around 20

ThatGuy34

i also reset everytime i fill up. pre-smarty overhead was 4-5 mpgs high. post-smarty overhead is 4-5 mpgs high

mnmlod

Mine is like playing the lotto!...I reset it every time to see what numbrs it feels like spitting out.

Dodgezilla

Back when I had my built 03 I was pulling about 12,000lb and I had a Ford owner in the truck with me. The overhead was showing 15mpg and he was amazed! Do you think I told him it was off??

Fisherguy, you are right that my overhead is still off because my speedo was never corrected but it still is telling me what my current actual mileage is. Now I just wish the number would jump up a couple of points...

RobG

On my 01, it was accurate til I modded it (injectors, box, etc), at which point I ignored it. On my 03, which never got modded, it was always +/- 1 mpg. On my current 05, it reads 2.5 to 4.0 high, and so far with the Smarty on 3, hasn't really changed. But I AM up about 3 mpg since adding the Smarty. I can now do 75 and get 17 instead of 14.

Comparatively speaking... two weeks ago I bought a 2008 Subaru Impreza WRX, and it has a MPG reading too. Around town, it will read about .5 to 1.0 high, but on the highway, it will read around 2 mpg low. That works out to 20-22 in town and 27-28 on the highway (at 75). It's a 5sp and a turbo, with only 1700 miles on it so far.

Biggest bummer is it requires 91...

Rob

paroxysym

my overhead is 2 miles off..

Tee

I have always figured it that the overhead takes some arbitrary distance that it calculates, cant figure out if it is close to one tank full or not. For instance, if I reset it at fill up and check it against hand calc the next fill up it is usually within .1 - .5 in either direction of my hand calc for that tank. Seems to be closer if I don't run the tank way down and fill up at 3/4 or 1/2 tank, (which I find myself doing frequently now as the heartburn is easier to take when its under a $100 dollar bill to fill up.) Now, if I don't reset between fill ups and just let it be for several tanks. It will be between .9 and 1.5 higher than my hand calc for the tank I just replaced.

So the question is, does it calculate from the last time you reset? or does it calculate over say the last 50, 100, 200 or ??? miles. That little piece of information would be helpful in deciding if your overhead is to be relied upon.

'06BlueRam

mine is always 5 to 7 miles off

dogger

Mine is definitely off but it does show the trend as I run a Quadzilla Standard box. If it is reading 21 MPG at 70 MPH and 24 MPG at 63 MPH, at least I know that I am getting better fuel economy at 63 MPH, gee go figure, slow down better fuel economy. The only accurate method is hand calculate over several tanks of fuel. Driving with a tail wind = better economy, driving into a head wind = reduced economy. Not driving at all = sucks!

L8r,..........dogger

Fisherguy

I have a Excel spreadsheet i got from one of the members here, I just put in the amount of fuel I fill up with and how far it got me and it spits out US MPG, CDN MPG and litres per 100km.

I can send a copy to anyone who wants it but the "input fields" are all metric for us Canadian eh?!