Looking at the past few months in my UK 2003 Jazz in terms of petrol fill ups.

#1
Car Reported - 47.2 MPG
Miles travelled - 321.2
Litres in - 33.29
Actual MPG - 43.86

#2
Car Reported - 45.4
Miles travelled - 308.2
Litres in - 33.03
Actual MPG - 42.41

#3
Car Reported - 47.1
Miles travelled - 309.1
Litres in - 31.65
Actual MPG - 44.39

And right now.
#4
Car Reported - 46.9
Miles travelled - 203.6
Litres in -26.06
Actual MPG - 35.51

The needle was at half tank and 26 litres went in, which makes sense since it's 42 litre tank! But 35MPG? I average low 40s in the winter, and mid 40s in the summer. And in the middle of June, it's dropped to 35mpg?!

Is it really bad MPG or can it be explained through another method?

Also, the difference between the car reported MPG and my own figures are usually 2-4 difference. Never a difference of 11.

 

Depending upon how you put the fuel in, you can fit an extra gallon and a half in the filler tube. I do it each time I fill up; after the nozzle clicks, I slowly and painstakingly dribble an extra 1.5 gallons or so in. The tube runs all the way to under the front seats, remember. If you already didn't know this, you may have had the inconsistent reading because of it.

 

Well I always stop filling once it clicks. Could it be clicking at different times whenever I fill up?

 

The pumps read the back pressure of the escaping air in the tank to determine when to shut the flow off. There is a little hole on the side of most nozzles that read this pressure. when the tank get near full the back pressure increases rapidly and the flow is shut off. This is something that can be calibrated by the pump manufacutrer and the station mechanics that maintain them. I am sure there is some standard that is followed, but depending on the fuel flow into the tank and many other factors (corrosion or dirt in the pressure tube) each pump will be slightly different. If possible try using the samp pump at the same station for this same test and see what you get. The results still may vary but should be closer.

I assume the Car reported milage is from the onboard computer that you have on the UK version. This measures the actual fuel flow at the injector and does the maths with the miles driven. My mechanic friends who own an independent garage always tell me that this is the only truely acurate way to determine fuel usage.

 

Yeah the car reports the MPG as I drive, the US one doesn't?

I've always been told the best way is to report the miles driven and the amount of litres in to work it all out.

But I guess if the tank isn't full all the time or it clicks off at a certain point, it could cause problems like this.

I guess that could have been what happened here but it definitely struck me as odd when I noticed the fuel pump not stopping till it hit £30!

Nevertheless, getting a nice 54 reported MPG from some motorway driving with AC on.

 

You mean 35 MPG is bad? I've been mixed up all this time, thinking that 35 was pretty doggone good.

I have noticed my car getting less fuel efficient lately, too. I choose to blame ethanol blending. I'm probably wrong, like that other time.

 

Heh well, I think the UK ones are slightly more economical and I'm sure there's also two kinds of gallons so you can't compare directly.

But the car is meant to get upwards of 50 even in city driving and I only get 40-45mpg.

 

No, When Honda brought the Fit to the US, they decided that all of the cool and usefull stuff that the other countries had, the US market wouldn't like it. So they stripped it down put in a larger engine and put it on sale.

We have a very basic dashboard with no on-board computer display. If you search you will find that people have added a Scangage to do this. No Sat-Nav option. No smaller engines for those who do most of their driving in the city. No arm rest in the center ( because everything in the US is so close that we don't drive long distances. )

The US version was an after thought, Honda didn't figure on selling them to anybody but college students and pensioners who drive to the market once a week and to see the firends in the next town over. They have since seen that they were wrong and the sales numbers were about 30 % higher than planned in 2007 and on pace to be 40 % higher in 2008

This isn't to say it isn't a excellent car, the US version just needs a few pieces and parts to make it complete.

Personally I would have liked the CVT and the 1.4L engine.

 

The OP is from the UK, don't forget that an Imperial gallon is 5 quarts as opposed to the US gallon which is only 4. So his 35mpg is like 29mpg using the US gallon.

 

This is more a response to the North American market viewing hatchbacks as economy cars, so that people are unwilling to pay Accord money for a fully-equipped Fit. While I'm sure many on this forum would be willing to pay more for a Fit with a higher equipment level, the NA market at large won't, generally speaking.

 

Ah, I see. So does anyone else here think Ethanol is hurting our MPG without really helping much of anything?
And what's the gas like in the UK?

 

Most of my gas is used up on the interstate but I am averaging 39-42 MPG and I am only using the ethanol blended gas, 89 octane, because it is the cheapest here in Nebraska.