As posted previously in many other threads, the MPG gauge generally exaggerates by 10%. I dropped my salesman a line about the innaccurate MPG estimates and here's what he had to say (with some content removed for brevity):

Can we get a movement going here to get as many folks as possible to call in with the innacurate results of their MPG gauge? It seems to me that this would be an easy programming fix for Honda to take care of, so if we make enough noise it will eventually be less painful for them to just do it.

Any other thoughts on who to contact besides the phone # above are welcome!

 

but I'd rather see a firmware update to make the car's true fuel efficiency equal to what the gauge says!

I've decided to call my dealer about it and see if they will do something. Although I don't think they will adjust it if Honda doesn't admit yet that it's wrong.

 

I'd call that Honda Corporate number, too. Personally, I'll +rep anyone who does and posts that they did so in this thread!

 

The other thing it might do is simply get the gauge removed for future revisions of the car...

 

i will call to complain too cause my gd3 doesnt have a mpg gauge but rather i had to buy a scan gauge.

maybe i can get honda to reimburse me for that.

 

Mine is about 4-5mpg high, but I still consider it a great tool.

 

Did the guy say if having a spreadsheet of the actual MPG figures would be helpful?

 

No, but I'm sure it wouldn't hurt.

 

They should have a better gauge that display how much fuel is used. Then, you can calculate how much gas was removed from your fuel tank and subtract that from your last refuel to see how much gas you have left. Then to figure out mpg, all you do is divide... even a sixth grader can do this sort of math. We don't need no fancy machine to do subtraction and division... just a $10 calculator maybe....lol... and not even a scientific calculator.



My fuel gauge is crazy...lol...it moves 2mm within 24 miles, but moves 2 inches within 24 miles at the end of the tank. (I'm Exagerating for those who don't get the joke.)

 

The problem with all of the in-dash mpg meters is that owners try to drive 5 miles and bthink they are getting true mileage. The metering inaccuracy and tank level reading is only about 1% and accumulatively that adds up to as much as 10-15%. Once you get over 100 miles the error has dropped soundly and it matches the refill if you can to it to the same level each time. (betcha can't)

 

I'm driving each tank to empty (300+ mi) and getting almost 20% error each time.

 

Holy Cow. Thats not normal on any of my cars with mpg meters.
Are you using stock size tires? Only thing I can think of that would cause that kind of consistent error except software problem.

 

Stock everything performance-wise.

For example, I had a 310mi tank that I calculated to 35.142mpg. The gauge said 42.4mpg. 42.4-35.142=7.258 and 7.258/42.4=.17 or 17.1% off. And that's calculating generously, because if I take 7.258/35.142 that's 20.6% off. All of my tanks have been off by a similar amount.

From what I've read on these forums, that's not terribly unusual. There needs to be a major fix on these gauges.

 

This is the easy solution. Just tell me approximately how much gas I've used!

 

Accuracy is not going to be a useful feature of this kind of system. It assumes the injector signal is precise to the fuel delivery. And it reads a gas tank level change withdifficulty as its not a nice regular shape. Sloshing don't help either. And the odometer is affected by tire size changes. Not just the tire size, i.e. 205/50x15, but also variations in the actual tire measurements.
Adding all those can easily produce 10% errors on long runs ( much greater on short runs) but your 20% indicates its defective and should be replaxed. good luck.
PS the cheapskates solution is knowing that at 3/4 tank the trip mileage should be 100 miles and at 1/2 tank 150 miles. If the full reading drops before 50 miles mpg is low. Remember the tank is not a linear volume change.

 

Here's my problem. Most people who have this issue are seeing the calculation being off by 15%ish regularly. It's not like it fluctuates between -8% and 8% off, which would be forgivable. All it would take is a small tweak in the calculations; subtract 15%, and the gauge would be nearly spot-on. I don't see why this is an unreasonable thing to ask for from Honda.

 

the point is they can fix it. if enough people complain about
it. it will be fixed.
I have had a least 3 cars with MPG indicators and none were
this far off.
i personally have seen a 4 MPG error all the way to a 8 MPG error.
thats just ridiculous.

 

Anything can be fixed; question is: can you afford it ?

 

Anuthing can be fixed. Qureastion is could you afford?
Did the scan gage specs say anything about accuracy? If it didn't there you are. If it did and it doesn't meet spec, the supplier either has to fix it to do that or refund your payment.

 

who afford it? i don't understand?
cars are under warranty. they will be fixed
under warranty.