Hey Fellow Fit Freakers,

I own a 2013 Honda Fit Sport. Purchased new, it delightfully gifted me with 30/city and 38-44 mpg highway! Now I'm lucky to get 29-33 mpg on the highway. Tires are rotated every 5k and check air pressure every month. Faithfully service the car when the maintenance light goes on, get oil changes (which is done at the dealership with the required oil) and replace engine air filter every oil change. I replace my own air cabin filter - which I don't think has anything to do with gas mileage? There's only 35K on the car, as I telecommute.

What are some things I can do restore my gas mileage? What could be happening? Thanks for your help.

 

When it gets driven is it city or highway? If those are easy/leisurely miles...just a guess, but I'd say it needs what they call an "Italian" tune up. That's a fancy way of saying it might just need to be driven hard and brought up to full temp and run there for a bit.

I'm betting that it has some carbon build up and the catalytic converter could be a bit clogged. Probably needs some heat and rpm to clear it out.

 

The smaller the engine, the more affected it is to any small change in gasoline blend, weather conditions, driving style, mechanical changes, etc. But how are you determining your mpg? My dashboard meter is always +/- 1 to 2 mpg different than when I hand calculate the result. I also notice the the mpg changes depending on how "aggressive" I am about filling the tank up to the top or settle for the second time it trips off.

I have a '11 Sport AT and I can fill up with regular, hop right on the highway, set cruise control around 60-65 mph and get 45 mpg. If I fill up and drive locally, sometimes gassing it (more spirited driving), I'll get 29 mpg. Going to work 5 days a wk, which is mainly highway but some local, I'll get 32 mpg. Winter is always worse mpg for me than summer. With and without the air conditioner running makes a difference in my mpg. I changed the tires from 185/55-16 to 205/50-16 and the mpg changed. I changed the wheels from the 16x6 to 16x7 and the mpg changed. I changed the catback exhaust and the mpg changed. But my 4.6L V8 Tundra is a "solid" 15-16 mpg for the last 4 yrs no matter what I do but I did see about a 1-2 mpg decrease when I changed from worn out tires to new of the same style.

I'm not saying that there isn't a mechanical change in the vehicle like a loose spark plug, valve clearances that aren't at their optimal setting anymore, etc but mpg vary all over the place the smaller the engine. Maybe your experience is due to something very subtle but it may not be anything to worry about. I run a 15 tank fill up average mpg statistic and that really evens it all out but it did show a problem (steady long term drop) when two of my spark plugs were loose. I was wondering why I would catch the odor of gasoline upon start up every morning.

 

It's probably been a little more city than highway, but I've taken it on several road trips as well. Thank you for this suggestion.


Thanks for the comment. I can see new tires and running A/C affect things. Had new tires put on last year and live in the desert. My poor Fit needed the A/C unit replaced first year back. I've been reading my computer's mpg average, that I reset on every refuel. Is this not accurate?

 

Chances are that if it's reading has gone down, then so has your actual, but no, they aren't accurate. Cars that I have owned have been off by as little as 1mpg and as much as 6mpg. Generally they are also the least accurate early in a tank and get more accurate when the tank gets low.

The only accurate method is to reset the trip odometer when you fill, run through a tank, and then divide the miles on the trip odometer by the gallons used to fill.

 

Have you had the same commute since 2013? I know Las Vegas has been steadily expanding, and with that, more traffic on the streets and highways. I experience more slow-down/speed-ups whenever I visit (as opposed to steady-state speeds).

 

Since your 5 year old car only has 35 K miles, it means you only do an average of 7 K miles / year, or about 585 miles / month, or about 20 miles / day. This is on the low side of the average, which usually means higher fuel consumption.
Is the car mainly being used for short city (stop & go) trips?
Or do you mostly use it for once a week long highway / open road trips?
You did mention you're getting only 29-33 mpg on the highway, however how similar are these new highway trips to the earlier ones when you used to get 38-44 mph?
Any difference in traffic, length of trip, cargo, passengers, outside temperature will have an impact on your mileage.

Before taking the car to a mechanic and potentially getting ripped off, try this experiment:

1) fill up gas tank & reset the short trip/MPG odometer.
2) get rid of any extra cargo/stuff in the car, and don't bring any passengers if possible.
3) drive on highway or open roads for at least 1 hour, preferably around 60-65 mph (in the slow lane, of course!)

Even without re-filling and calculating, just looking at the dash computer, you should be getting at least 35-40 mpg, and maybe up to 45 mpg. If you're only getting 30 mpg during this trip, then it means there could be a mechanical issue with your car and only then should you get it checked up by a mechanic.

Another suggestion I have is try some fuel system cleaner with upper cylinder lubricants, like the Lucas UCL Fuel System Cleaner, or the Marvel Mystery Oil.





ALSO - why do you change the engine air filter with every oil change?
I've bought my car with 24 K miles and changed it then simply because I wanted to & it's cheap to DIY. The air filter was pretty clean and seemed to have lasted much longer.
Over the next 3 years I've put almost 40 K miles and recently changed the air filter. Again it was still in decent condition, and same as before, I've changed it more for peace of mind.
I am positive I could have used the same air filter until 50 K miles, maybe even 60 K before it got real nasty, but since they're so cheap, there's really no point in pushing it that far.

 

+1 on MMO, that stuff is literal magic

how about a scangauge? it could potentially teach some good driving habits ....






here's my personal best ...52.4 mpg per honda mpg/48.9 mpg per sg2 ... this was a 76.5 mile journey from San Diego, to the city of Irvine up the 5 Fwy. this is a testament to how awesome a scangauge (or similar device) is

 

try the lucas fuel cleaner first.

 

Sometimes, I wonder if any of the hundreds of fuel treatment products really do anything other than empty the wallet.

It appears to me that while experimenting, I created a "boiler maker" (malt liquor mixed with a shot of hard liquor) in my fuel tank and experienced the same disastrous results one would expect as a novice to the drink. I must have had Lucas / Seafoam / etc fuel treatment in the tank already when I added the Lucas Ethanol fuel conditioner with stabilizers. Within short order it started to emit a "noxious cloud of death" that would immediately choke you if nearby. It was visible too, like a big moisture / condensate cloud, which stretched maybe 50 ft from the back of he car while I drove in 30 - 45 mph range. I saw cars behind me back off to about 200 ft back, so they were picking up on it too.

I decided to aimlessly put on mileage to burn up the tainted fuel and dilute with new until gone from the system. As you can see, it appeared that my catalytic converter was taking a puke too and redepositing itself on my exhaust tip. I would periodically use very fine steel wool to remove these deposits that were noticeably hard / 3-dimensional like ceramic / metal. My Check-Engine-Light never came on indicating that the fore / aft O2 levels were out of wack (cat not working). Eventually the cloud was gone, the orange deposits stopped, gas mileage didn't seem to change + / -.

I guess my suggestion is to not "mix drinks" and only do one thing at a time to see if there is a benefit.

 

@ HondaFitChick2018

I thought of something else that could cause your lower mileage and many people put these things on their cars and leave them on year-round even though they only use it 1-2 times / year.

Do you happen to have a roof rack installed on your car?

Depending on make and model, a roof rack can hit you with up to 10% penalty on MPG.


@ spike55_bmw

Thanks for sharing your "mixed drinks" experience. It definitely sounds like a bad idea.
On the topic of fuel injector cleaners, some appear to be better than others.
From my research, Lucas ULC and Marvel Mystery Oil are 2 of the better ones, being recommended by many users at Bob Is The Oil Guy (BITOG) forums.
I've personally noticed minor MPG increases after adding these to the gas tank during a fill up, but only lasting during that particular tank, no noticeable effects when using plain gas after.

 

They're all snake oil.

 

HFC2018 , are you using Top Tier gasoline ? It's recommended in the owners manual . Go to these for info and list of Top Tier gasoline providers . https://www.toptiergas.com/ and https://www.toptiergas.com/licensed-brands/ . I use Chevron Techron Complete Fuel System Cleaner 2 > 3 times a year . Redline SI-1 ( https://www.redlineoil.com/si-1-comp...stem-cleaneris ) is said to be a good cleaner at B.I.T.O.G..

 

It's a waste of money to change your air filter that often.

Here's a theory- your tire gauge is off. Try a new one and see if you get the same readings.

Especially if you're using the pressure gauge built into a pump (either your own or one at the gas station).

 

The winter blend is here too . That could impact gas mileage .

 

Hypocritically, I occasionally run a bottle of Techron. BUT..
Here's what my owners manual says about Oil Additives:

Engine Oil Additives Your vehicle does not require oil additives. In fact, they may adversely affect the engine performance and durability.

Therefore, I doubt the OP's problems are because of need of an Oil Additive.

 

I think you mistook fuel additive for oil additive. Guessing neither is suggested, but they are two different things. Remember Slick 50? That was an oil additive.

 

No, I mean I say Hypocrite because I suspect BOTH fuel additives and oil additives are mostly snake oil. But the quote from the manual is a direct copy and paste. And I know it say's Oil Additives.

I don't think I would use an Oil Additive.
I occasionally run a bottle of Techron.-Fuel Additive

Just pointing out, that from Honda's viewpoint, they don't even recommend using ANY Oil Additive.

 

Sort of fell into this post while searching for another, sorry to bring it to the top if things are resolved.... I know your mileage is fairly low but I would highly recommend cleaning the MAF (Mass Air Flow) sensor. Your parts store will sell CRC Mass Air Flow cleaner. Watch a few videos and follow directions and you cannot go wrong. Best of luck!

 

it could be a change to the car (heavier wheels?)
it could be the maf
it could be the alignment
it could be spark plugs
it could be winter blend gas
it could be the drivers right foot


Op didnt provide much for us to go off of. and by the looks of it (1.5 months since the ops 1st and 2nd/last post) .... we'll prob never hear back anyways