You definitely have an issue somewhere. The first thing I'd do is spread out some newspaper and park over it overnight. Maybe you have a pinhole leak because that seems like an awful lot of gas to go through. You are 8-10 MPG below normal. Start with the most basic and move up from there. BTW, how much gas did it take to go from 1/4 to full?

 

8.13 gallons. I called a Honda dealership and told them my car runs fine except for the horrible MPG. He told me to go to the same gas station and the same pump and fill up until the gun clicks off twice; once I've done 3 fills like that, he said to call Honda Canada with the stats. Two more fill ups to go.

 

you have made sure your calipers are not sticking?
I was dowm to 300k on a tank of super.just did the sticky buggers today.only noticed it was not rolling as it should.was getting 400k on reg.

 

How close is your dashboard mpg to your calculated mpg? If the dash reads way way higher than your calculated a leak is present. If they are pretty close that's not the problem.

The computer does not know how much gas is in your tank not does it care.

 

Thanks guys for your input:
@jbbuilt: I brought the car in this summer for a full checkup at a dealer and it came back fine. No valve lash adjust, change brake fluid (done since then), brakes were at 85% life etc. How do I check for sticking calipers?

@wanderer: what's dashboard mpg? I have a GD3 sport manual and don't have any onboard MPG monitor. I just input my odo reading and the amount of gas I purchased from the pump into Fuelly; I figure that's about as accurate as it gets unless I do very small fill ups where the margin of error would be greater.

To those suspecting a fuel leak: I frequently park my car in same areas and never noticed any gasoline stains on the ground especially. It should be evident on my parents driveway. Wouldn't a fuel leak be pretty obvious? Also, I'm a fan of the newspaper idea but it's winter and there is snow everywhere. Wouldn't fuel stain white snow? Come to think of it, I don't even know the color of the fuel that goes in my car. Is it clear? (I.e. I wouldn't notice a leak on snow)

 

Pretty easy check.Are the rims and caliper warm,hot to touch after a short drive.Jack up front ,spin the wheel in neutral.Do they both feel the same?Jack up the back too and check your rear cyl while your at it.Make that baby roll.
Leaking gas you would smell if its any amount worth a worry, look around the gas pumps to see what it looks like.Always a spillover round there..

 

Last fuel up registered 19.5 MPG. 2/3 fuel ups before I call Honda Canada. I honestly don't know what someone over the phone will be able to do for me. I'm thinking more and more this might have to do with a dirty MAP or IAT sensor. Anyone know how to inspect/clean these?

 

Just started using Ultra-Gauge. I'm pretty happy with it. It is reflecting the MPG I'm getting at the pump. I'm getting an average of 14-19 MPG. I'm thinking more and more it has to do with bad coils and my engine running too rich.

When coasting (even in gear) my instant MPG varies between 40 and about 75 MPG. However, when accelerating from a standstill my MPG go down to between 6 and 20. So any time driving until I get to 3rd gear is sub 20 MPG range. I noticed how important the road inclination is. A slight hill will bring me down to about 25 MPG whereas a slight downward slope will knock me up to 35-40 MPG.

If I am coasting on level ground in 3rd gear I'm at about 30-33MPG. A slight press of the accelerator to maintain speed will take me down between 25-28 and a bit more of a press will take me into low 20s. If could just get from A to be without touching my accelerator, I'd be getting like 40 MPG .

So to make a long story short, it seems as soon as I touch that accelerator (even slightly depressed for maintaining speed) my MPGs drop to low 20s. I'm NOT using a throttle controller. I bought an engine air filter and I will change it tomorrow to see what kind of improvements or lack thereof I can see.

 

Update:

I just got done doing what the mechanic at Honda Centreville in Montreal told me over the phone. Since I had the car inspected over the summer and it came back with a clean bill of health AND the car has never thrown codes he said to do three fill ups at the same gas station and same pump. I have done that. My readings are as follows:

Date Miles. Gal. MPG. $$$
21/12/13 129.2 6.54 19.8 5.069
12/12/13 122.4 6.28 19.5 5.125
30/11/13 146.6 8.13 18.0 5.107

The person from Honda Canada says many different things can influence MPG and to take it into a dealer for testing if I feel it's not working right. However, the dealer has told me since there are no ECU codes, there's nothing they can do. Dealer says call Honda, Honda says go to the dealer...

Also, I have examined the wheels and there is no sticking caliper and the wheels seem to turn freely. It seems I'm up the creek without a paddle. I'll still call the dealer on Monday to try and schedule a fuel efficiency test. If that comes back empty, I'm gonna do the valves, coilpacks and plugs even if the dealer said everything was ok from the inspection they did this summer. I might also try switching to 0w20 (instead of 5w20) to see if that improves things.

It's too bad, I thought this car way the ideal city car but it seems my car is perhaps "special" (bad engine break in perhaps?) and that short trips combined with other factors has it consuming a lot of gas for such a little engine. I do have an HFP muffler, I'd don't know if that also might have an incidence on MPG.

I'd like to thank everyone that contributed their tidbit of info; it seems even Honda Canada can't give me a straight answer as to if this is normal or if anything can be done about this fuel consumption that is about 50% lower than the # published by Honda.

 

I feel your pain bro.Just filled up today. 33 L got me 237 k.slight aggressive city driven

 

Man that sucks! Why are we getting Subie numbers? Mike410b lives in Wisconsin and gets about 6.23 L/100 km. I mean it must be cold there too. Unless he does only highway. With some highway I can bump my MPG to high 20s.

I'm thinking we have bad coils. Lemme know I'd you change them and if it creates improvement.