Looking to get a few more years out of my 2011 Honda Fit CVT/NAV (118K miles)

Does anyone have any information if the car's computer manages the CVT gearing?

I'm going to likely be doing a lot of 1k mile trips (almost all interstate, 80% 70mph) in the future, and I'm pretty sure a better ratio for 5th would result in better highway mileage.

my average speed is around 70+ and getting 26-27MPG isn't much better than my old 1997 Mustang Cobra got on the highway (Cash4Clunker'd for a 2009 M/T Fit)

Pretty sure that turning 2K rpms at 75 would be fairly gas efficient, compared to the 3K rpms I'm seeing now (and my M/T was worse at about 4K IIRC)

 

Not 100% sure on this but, I don't think 2011 Honda Fits in the United States had CVT auto transmissions. I believe they have traditional automatic transmissions. After reviewing the service manual it doesn't show anything regarding CVT transmissions.

 

There is no CVT trans for any US spec 2011 Fit. Plus CVT's don't have gearing, they are single speed.

There is also no ECU upgrade for the transmission.

 

As stated above, you have a 5-spd automatic transmission, not a CVT.

At the speeds you're trying to drive, you're fighting against aerodynamic resistance and your mileage is going to suffer. That's just physics. Your comparison to a Mustang is an interesting one. A reasonably aerodynamic car with a powerful motor can be relatively efficient at higher speeds because the motor isn't being worked all that hard. That's why a Corvette (relatively aerodynamic) can get 30+ mpg cruising down the highway whereas a Chevy 1/2-ton truck (brick on wheels) with essentially the same motor is lucky to see the low 20s. There are obviously weight differences involved, but I'm making generalizations to illustrate my point.

Conversely, the 1.5L 4-cyl engine in the Fit is working hard to maintain 70+ mph. To mix some metaphors, you're bringing a knife to a gun fight. It's not just engine rpms or gear ratios you need to consider, it's also engine load. Even if there was an easy way to do it, I don't think a stock Fit could maintain 75 mph at 2000 rpm, even on a flat road. The engine load (fighting aerodynamic resistance) would be so high that the car would never stay in top gear (A/T) or would just decelerate (M/T).

The fuel efficiency gauge in the cluster, although often not accurate (mine is consistently low vs pump calculations), is a useful tool that can help you understand the relationship between speed (= aerodynamic resistance), engine rpms, and engine load. If you pay attention to your instantaneous efficiency, either with the gauge in the cluster or with something like a Scangauge, you'll see that in the Fit slowing down to even 65 mph helps a great deal.

I drive a 2010 Fit Sport A/T and just did an 800 mile round-trip this past weekend. Almost all interstate with 65 mph speed limit and I drove 60-65 mph. I don't speed, and I drive in a sensible fashion. On the 400 miles to my sister's house (net uphill) I averaged 38.1 mpg. On the first 285 miles of the return trip (net downhill) I averaged 44.2 mpg. I haven't filled up again so I don't know the final tally, but I drive this route 4-5 times per year and these values are consistent with my typical non-winter averages.

It is entirely possible to get good fuel efficiency in a Fit. You just have to make it a priority and drive accordingly, plus there's all the obvious advice about proper maintenance, tire inflation, not carrying unnecessary weight, etc.

 

Thanks. I think I got confused about CVT and VCS

 

26-27 MPG seems poor, even at 70-75 MPH. My '09 AT would get around 35 MPG at that speed. It even gets 28-30 MPG towing a 500 lb. trailer at those speeds.

Are you still on the original spark plugs? That could affect fuel consumption. Also, use the gas pedal gently to try to keep the torque converter locked up in fifth gear as much as possible.

 

I will look at doing that. I bought the 2011 in 2018. The lady who owned it put every maintenance in the book, so will have to look.

When on the highway on long segments, I"m just in cruise control.

Appreciate the suggestion.

 

Cruise control is okay for fuel efficiency on flat ground, but will reduce efficiency in hilly conditions.

As an example, where I live there are many rolling hills. I can carry a bit of speed into a hill and therefore reach the top without the transmission downshifting. Cruise control doesn't know the hill is coming so will have to downshift one or two gears to try to maintain speed going up the hill.

Similarly, as I reach the top of a hill I can start to let off the gas, knowing that gravity will help maintain my speed on the downhill. On steep hills I downshift to use engine braking to stay around the speed limit. I rarely use the brakes on a downhill, as that's just turning the fuel I just burned into wasted heat in the brake rotors. As with many newer cars, if you completely let off the gas on a Fit the fuel injectors shut off and you get infinite fuel efficiency when coasting. If you have something like a Scangauge or Ultragauge you can see that when cruise control is engaged the injectors never shut off and so you lose some efficiency, even if it feels like you're coasting down a hill.

Lots of little tricks to improve fuel efficiency. Each one might only have a small effect, but if you gain a bit going up each hill, and then a bit more going back down the other side, and a bit more when you find the timing of your local stop lights, pretty soon you're increasing your fuel efficiency by a noticeable amount.

 

NoVA to FL is pretty flat.

Appreciate the recommendations. Will be replacing the spark plugs, and will see if I can do better than 26-27mpg.

 

Core issue with poor gas mileage would be the O2 sensors. Spark plugs do minimal with gas mileage unless they are misfiring. Air filter would be next. But they are all intertwined.. Bad O2 sensors can foul out plugs.

 

I'm at 118K miles on the car. Got it with 79K. Had an emissions inspection last summer and it passed. Checking the service manual, at 62K it reported misfire on cylinder 3, they found a loose plug and only the one spark plug replaced.
[limited notes, the woman who owned it had a pile of receipts, then transcribed them into the service manual the day I picked up the car]

Since I have to pull the wiper cowl for the plugs, i'm gonna replace the ignition coils at the same time, since it appears plugs have never been replaced (and some Honda site says 30K for plugs...., for whatever that's worth)

How do I know if my upstream O2 sensor is bad? Wouldn't it log an OSD error?

 

If the O2 sensor was truly bad it will throw a code for out of spec as the voltage would read incorrectly when comparing to the other O2 sensor. It possible that it still working just not as well as it should.

Spark plug life depends on the type.. Platinum and Iridium are rated for 100k at least. Normal copper type plugs are rated for about 30k. However you can change them earlier as you like and they can foul out earlier if the O2 sensor is not working properly. The ignition coils usually are good for the life of the car unless they are burning out or not sparking at all. It won't hurt to change the coils, but I think that's unnecessary if you are not experiencing any misfires they will either fire or not. It wouldn't hurt to change the coils and keep the original ones for backup in case one of them do go bad.

If you are going in to replace the plugs I recommend using NGK plugs as they are OE for most manufacturers as well with the O2 sensor.

 

Coils, plugs, valve adjustment, air filter, drive 60-65 instead of 70-75, make sure tires have air in them.

If that doesn’t have you around 32-34 mpg, there’s something ‘wrong’

 

Tire pressure is probably one of the most important aspect of these cars. The lower the tire pressure say 26-28 psi or lower will cause higher rolling resistance and thus lower mpg. Optimal for factory tires is 32-33 psi. The car should roll on its own very easily on slight inclines if it doesn't or is hard to push by hand.. then the tires are too sticky and/or pressure is too low.

A lot of people are proud about buying the most high performance sticky tires for their ride.. not realizing they are just creating a higher rolling resistance and making the low hp Fit even slower.

You should note what kind of tires you are running (size and type) as well as the psi in the tires.