Even if this theory is true, the gauge is displaying information generated by a microprocessor; software should be able to compensate and generate a corrected output that would be much closer to actual MPG.

 

Everyone's definition of "in town" or "city" or "highway" is different. It's only when the same car covers the same course that we can really measure who is getting what.

I've posted this many times, it's a Motor Week video (or text if you'd rather not watch the movie) over on Fuel Economy.
Tips to improve your Gas Mileage

That begins to illustrate how driving habits change fuel economy.
Winding rural roads:
Comparing notes, it's clear that Henry's exuberance cost him, as he ended our first leg with an average of 17.6 miles per gallon. Dennis pulled in with an 18.4 MPG figure, a 4% improvement.
Highway:
On the highway, our drivers returned a high average MPG of 24.4, and a low of just 17. That's a 43% difference! Here efficient driving works out to be an extra 140 miles of range per 19-gallon tankful.
Traffic:
We then wound up our test with a stretch of stop and go traffic. Again, our mileage was closer, but Henry's aggressive technique still cost him a 2-1/2 MPG penalty.

But when I look at the video, I see I don't have any rural roads. My route is short, but the roadways are laid out in such a way to make bottlenecks everywhere. Including at the shopping center. My "traffic" far exceeds their "traffic" during busy times.

The way we could compare would be to follow each other around. If there's a way to stretch MY gas on MY route, I certainly want to know about it.

I don't use the A/C. I don't use the stereo.

And no matter which way I go to do the farther shopping, it's uphill. LOL! Sure, I get to pretty much coast in many areas on the way back, but I still have to get up the hills in the first place.

THAT will suck the gas up. Hills.

I guarantee we'd all have sucky gas mileage if we had to drive UP this road:

I love those travel blogs.

I got way better mileage on a long (for me, about 60 miles round trip) trip, that was mostly flat freeway. Once the car was up to speed, it required very little to keep it going and I enjoyed watching the digital mpg tick up a tenth of a mile here and there.

 

This doesn't make sense. It would not be an average MPG indicator if it was just determining Engine Efficiency. Since your engine has nothing to do with Miles (which requires the Transmission, wheels, etc...) it must take into consideration other factors. It is pointless to have a MPG "computer" if it isn't actually going to calculate Miles per Gallon.

~SB

 

Taffetawhite has it figured out - regardless of actual accuracy, when you do something efficient like coast it goes up, when you do something inefficient like idle or go WOT, it goes down. If you keep the bar on the high side, you'll maximize your fuel economy regardless of the actual number.

 

Just filled up the tank. Put in 9.6 gal and went 406 miles. Calculated Average was 41.89 and the computer said 46.9 so my computer is about 5mpg high.

~SB

 

Several years before the Fit's introduction to the US, the Fit/Jazz was made for ROTW (the Rest Of The World) - a mysterious, some say mythical place.

ROTW includes Australia, Britain, etc. which use strange units called Litres or sometimes The Imperial Gallon (the US gallon is 20% smaller). Maybe the Mpg Algorithm is designed for The Imperial Gallon... or is shoved between the two so either way Honda doesn't have to bother with two versions.

It would be interesting to see if someone in Britain or Australia were to change their display from liters to gallons, if their's act the same way (when using the appropriate conversions from liters to gallons). In other words, see if there are market differences.

Paul

 

No, it's not. The error is constant, just subtract the 10% MPG difference and you have you true mileage.

If you are using the same pump every time the error will be constant.

 

you can't base it upon separate tests and then average out the error you have. You have to base it upon the entire lifespan of the vehicle. You could drive 2 50 mile shots in a row (all city) and get 8mpg difference than the computer on each, then do a 400 mile run and get a 2mpg difference from the computer. your average wouldn't be the 8+8+2/3 which would be 6mpg error. it would be much lower than that and closer to 3mpg because you are calculating over a much longer period of time. If you want accurate stats, you have to calculate over extended periods of time. as for the Pump Error being constant, that'll never happen. Temperature, humidity levels, last adjustment time, Last batch of fuel delivered to the gas station, etc... will all be variables on a single pump so even driving the same route, going to the same pump, filling with the same gas, etc... will yield you different results. there is no such thing in real life as a controlled environment/experiment when it comes to fuel economy. The best you can do is average out over extended periods of time. What you will find out quickly is if you got a bad tank of gas....

~SB

 

If is is an efficiency guage, not tied to true mileage, they may just as well have installed the old vacuum guage my father had in his 65 Chrysler.

 

I just use mine for instant feedback on driving. For mileage computation, I do the old 'miles traveled divided by gallons used' thing and am happy every time! The mileage estimate on the guage is pretty consistently off by 3-4mpg's.

 

I second that. I was shocked when I found out they are still making cars with drum rears.

 

FWIW, I recently spent several days with my parents' ten year old Lexus RX300 and went through four tanks of gas. That thing has an absolutely accurate fuel economy gauge. When it says 20 mpg, it means 20 mpg.

I mean, if a ten year old Toyota/Lexus has an accurate gauge, Honda can build a car with one, can't it? On the other hand, all that gauge in the Lexus did is remind me what a fuel-sucking hog it was...

 

My gauge reads in l/100km (a kludge of a unit, but that's what people use)

It's inaccurate about the same % and in the same direction. ie optimistic.

I think it's just what a prior poster said. Honda figure most people won't bother doing the calculation and they will tell people their car is getting 10% better consumption than it really is.

I guess they didn't figure on Wheels Magazine and the Sydney Morning Herald calling them on it and threads in forums like this one.

 

Mine displays l/100 km (I don't know why all cars do this when the term/measure used by people is km/l). I only filled it up twice and only measured the second time. The display read 6.3, but i calculated 6.7.

That's a huge difference and like the rest of you it's to the optimistic side! I think the computer should be able to keep pretty good track of the actual amount of fuel injected making it easy to calculate - my old Renault Scenic was spot-on, both in l/100 km and it's reading of fuel consumption in liters.

 

What is the point of this gauge anyways? I have driven for 50+ years without such a gadget and managed quite well. Rather useless really.

If you want to know your mileage then calculate it over a few tanks.

I am getting 42-44 mpg on an Imperial gallon. I hate the damn L/100km thing.

 

The point is that it's nice to know your mileage and to have the computer do it for you is convenient! Like remote controls and lots of other stuff you can manage quite well without, but still a surprisingly big share of people have them and would rather not be without

 

I tend to agree with ThomP as it is nice to have but not a necessity. it is also a great reminder to try and conserve fuel. Kind of like a game that others mentioned above. I've done without for 18 years and I do Calculate every tank and keep a log of it. The one big benefit of having this gauge (and not keeping a running log) is that if you have a few tanks back to back (or just one tank) that are way off and you haven't changed your driving style, you know you may have a problem. We had an issue like this with my dad's Rabbit Truck. The mpg dropped from the 40's down to the high 20's. Found that there was a minor problem with one of the plugs. replaced it and the economy went back up. If we hadn't kept track of the economy, it may have taken longer to notice.

~SB

 

I'm still on my very first tank of gas, and it just sneaked a teensy bit below full after three days of city driving. I would have consumed almost a full quarter tank on my cougar. Numbers aside, I'm freakin thrilled! LOL! I watch my MPG meter and it indeed is training me a bit to drive better. Also, working overnight I have the luxury of no traffic to and from work so I make good use of cruise control and that also seems to help a great deal- especially until my foot locks in to the feel of the gas pedal, which is quite a bit different than my old car; more responsive.

I AM NOT A NUMBER! LOL! And I'm sure getting TONS better gas mileage now baby!

Dan

 

What is this madness? The car is ~64% front ~36% rear weight distribution. multiply that by the natural tendency of the vehicles weight to shift forward durring braking and you realize the rear breaks do little in our vehicle. The torsion beam suspension helps a small amount as the rear will tend to 'squat' somewhat durring moderate breaking but still, rear rotors/calipers are not particularily needed.

 

I'm still on my 1st tank and reading 32 mpg after half used. Realizing it's still breaking in, I'm happy with that after trading in my Ford Taurus guzzler.

Now to some of the stories on this site about mileage, on this and other threads. I'm 55 and have owned a few cars in my life and always checked my mileage, not religiously, but often. I'm sorry, but I'm having a hard time believing some of the claims that are being made. Sure you can get a little better than EPA estimates if you really watch how you drive..........but I think we have some Pinochio's trying to out do each other.

The man next to my house when I was growing up, used to tell some whoppers about gas mileage. My dad was like me, as he always wanted to believe people and would fall for the stories. I'm like that too, but no more.................when reading these stories, my inner monologue is going to start calling "BS".

There's a couple extra gallons being crammed vs the previous fill-up or something. Maybe some of these guys accidentally received a top secret prototype that slipped through the US governments testing site...... "We always knew they were hiding high mileage cars, in a conspiracy with the oil companies".

Pretty soon someone will be claiming that their Fit is manufacturing gas and that they have to pull into a gas staion to get some siphoned out every 100 miles.