markp

Thanks for you folks responses. Now I just wonder what causes the offset between hand calc and overhead. However if my Ford/Chevy friends go for a ride I will make sure they look up !!

pik

Mine is the same.

chamisi

mine is always 15.4 it must like that number I assumed the edge was screwing with it so I don't pay much attention to it when the needle is on E I fill it up

Fishaholic

The more city driving or idol time seems to make it off more. If you fill up and drive on a trip it is usually within .5, atleast on mine.

pullin hard

love the avatar
just put a piece of tape over it, or switch to temps.
they are hardly ever right, due to so many differences between trucks, driving style,tire size,etc
i think mine read a little on the high side.i just fill up, and record my milage, and then do the same thing couple days later.always seems to be within 100kms,depending on how i drive.

SOhappy

Of course, I don't mind it reading a little high. I had two instances in the past three weeks where a friend and then a co-worker chided me for driving such a "big gas-sucking pickup" (their words, not mine) at times like these. The first has an old furd aerostar (last one running on the planet?), the second drives a Nissan Titan (). Both times I motioned them over to see my readout. The first time it said 20.x mpg, the second time I'd been doing a lot of highway driving and it said 22.5 mpg. Other than "Ohmygosh! That's better than my vehicle gets!", that shut them up in a hurry.

Oh, and you shoulda' seen the look on my brother's face- the one that can't get better than 12 mpg in his 6.4 F-350 when mine was reading 24mpg the other day. Priceless!

austin1972

I filled up after loading in my new smarty jr. (set on economy). So far, it says 26.6 on the overhead

It'll be interesting to see what the hand calculation comes out to at the next bank heist - I mean fillup.

DiezelSmoke

My wifes Passat shows 46mpg and we have never gotten better than 42mpg hand cal.

DaveB.inVa

I consistently get right at 10% higher on the overhead. I have an excel spreadsheet for about everything in my life from my vehicles mileage, maintenance, rounds fired in my firearms and reloading data for my .45.... ect!

I do average just under 20 mpg hand calculated though with the overhead reading about 22 mpg.

There was a definite increase in my mileage when I added the Smarty, it is easily observable on graphs from my spreadsheets. Unfortunately the graph for diesel prices over time seems to rise exponentially!

Pull Dog

Hand calculation on mine last week was 20.2 and the overhead showed 20.4 so I don't have an issue with the overhead being slightly off. Getting a good fill on the tank on the previous fill up could have caused my hand calculation to be off somewhat! I have learned to trust the overhead.

05HDRAM

I think it's silly if you use the overhead for anything other than an estimate. That is all the over head is doing, estimating mileage based on how your driving.

ShaneCTD600

Same here, 4 high no mater what the weather or situation.

NickBeek

My overhead was consistently 2 over unless I had my quad xzt hooked up then it was 4-5 over. I removed the quad and had my injectors replaced with new stock units and now it reads 4 over all the time. I have reset it and drove around in town and it went up to +4 then I reset it and drove highway and it went to +4 again. What I want to know is when they look at it in the ecm with their scan tool what does it show, actual or fantasy land? There is a place on the starscan tool that shows gallons consumed and miles driven.

TreeFarm

I get what the OP is saying. There is no flow meter on the vehicle, so the computer has no way to know exactly how much fuel is going into the engine. To compute mileage, it must use some sort of predictive algorithm, and there is going to be some degree of error.

Somewhere in the design process, someone had to decide how much error was tolerable, and whether or not it should be biased at all. Since most vehicles tend to compute better mileage than is actually achieved, and by a fairly significant percentage at that, it seems likely that a conscious decision was made to have it read high.

I'm not sure it's a scam, but I don't think it's ethical. If it had been done ethically, we would have roughly as many reading low and we have reading high.

I suspect this is typical throughout the industry.

RAMRODD

It has to be a scam and just about every make is doing it. Why do you think the gauge stays on full so long, Last quarter sure seems to go fast. I don't think I have heard of someone saying they are getting 15 mpg but the computer says 13. Dodge does it close usually within 1.5-2 on a stock truck. My little VW TDI is off atleast 8-10 and anything under 15 is in VW specs. Not to mention VW speedo is reading 3-4 mph fast and their is nothing the dealer can do about it.
When it comes to these CR engines and everything is stock I bet they could be within .1 mpg if they wanted to be