Here is the data from my first test of the ECON button. On = 52.6, Off = 48.0

• AC was off
• Mileage was increased by 11%, but this is NOT conclusive, see disclaimer below
• MPG figures of 52.6 and 48.0 are from Fit's trip computer, which is 3% optimistic according to my tests here
• I got caught at a long red light with the ECON button off
• I already drive slow like a hypermiler, diminishing the ECON mode's ability to help a driver slow down by dulling throttle response

I drove the same route under similar conditions, once with the ECON button on and the next time with the ECON button off. The AC was off for both trips. The ECON button increases the efficiency of the AC so the MPG difference would be larger if the AC was on. As a hypermiler I try to accelerate slowly, minimize idling and avoid speeds above 60 MPH. The ECON button might have a larger affect on a driver who does not use hypermiling techniques because the ECON button unconsciously helps the driver accelerate more slowly with its dulled throttle response.

I will update this post as I perform more tests, such as an ECON button test with a more realistic scenario of the AC being turned on.

DISCLAIMER
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This is only one trial. At least 30 trials are necessary to glean statistically significant data. I got caught at a long stop light for the 2nd trip with the ECON button off, unfairly lowering the MPG.
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Here are some graphs of instantaneous MPG measured at 10 second intervals. The only conclusive data I can draw from these graphs is that the ECON button makes it easier to maintain consistent throttle. That is why the blue line is jumpier.

There are a few stoplights at the beginning of the route, and one near the end. When the ECON button was on, only once did I come to a complete stop because I was lucky enough to creep up to the red lights without fully stopping. When the ECON button was off, I was less lucky with the red lights, possibly influenced by the more sensitive throttle control which made it harder to drive smoothly thus less able to creep up to red lights.





Related Threads

I created some animated charts which show the effect of traffic on MPG here

https://www.fitfreak.net/forums/3rd-...ml#post1253803



I used a Bluetooth OBD scanner to feed telemetry to my phone, running the Torque app, then exported the data to a spreadsheet. For more information on how I gather telemetry see this post:

https://www.fitfreak.net/forums/othe...ml#post1251982

 

To properly measure the difference between ECON on and off, a reasonable number of tanks will need to be driven under each and overall averages compared. Personally, I get enough variation from one tank to another even with it consistently on and thinking I'm driving about the same that I wouldn't know if ECON had an effect over a single tank's comparison. I've now had quite a history with it on all the time, so I'm thinking next fill-up after I get back from my labor day weekend trip I'm going to turn it off for the next 5-6 tanks and see how it compares over that time. I fill up about every 3-4 days so I expect that it'll take nearly a month to complete. I don't see any quicker way of doing this accurately.

 

Yes I agree. My test isn't really all that helpful. What you said sounds like a great way to test. Please share your result. I thought about turning ECON off for at least a tank, but my hypermiler mentality makes it tough for me to willingly harm my own mileage.

 

Believe me, it pains me to think about the possibility of dragging my overall MPG down. I'm only at slightly better than 36 now because I live in such a hilly area and also spend a chunk of each tank either in traffic or doing stop and go at red light after red light. But that 36 is hard earned by doing everything possible to be efficient under those conditions. Should this drag it down a couple of MPG, I'm going hate it, but curiosity has been killing me particularly since no one else is doing it. I guess I'll be the one to take the hit!!

 

just curious how do you drive less than 60MPH on the freeway? I have a daily 80 mile one way commute that I drive at 4:30 AM, so driving conditions are identical every single day. I set the cruise at 65 MPH at mile 3 into the trip, and it doesn't turn off until the last mile. This driving at 65 thing took massive discipline, helped along by the fact this car doesn't like cruising at 80-85 like my other cars. 65 already seems SO SLOW so I was curious how you drive even slower on the freeway... I am getting dangerously passed on all sides at 65 already (by semi trucks too... that made me sad).

 

Here in the Atlanta area, large portions of the freeways never allow you to approach anything like 60 MPH during rush hour. Rush hour is a mistaken label. it starts really early in the morning and goes on until nearly 10 AM. It starts again at around 3:30-4:00 and continues until 7:00 or later. The entire northern arc of I-285 is a parking lot during those times, and most of the I-75/I-85 connector going through town and all the way well north and south is the same. Also GA-400, parts of I-20, and a few others.

I used to spend a large part of my drive doing no more than 30 MPH peak, with long periods of no movement whatsoever before creeping forward a bit. My average speed for an entire tank (last car measured that), even averaging in the parts of the drive where I could actually go 70-75, was only like 33 MPH or so because of all that non-movement.

 

For this test both drives were at 9:30pm on a four toll road, so there was little traffic.

During rush hour it often isn't practical to go any slower than 60 mph, however if there is another slow moving vehicle, like a truck, you can just get behind them and join in on the preexisting slow lane.

Here is a graph of my speeds. The fact that those lines are different pretty much makes my test invalid. Although, I did find that it was harder to limit my speed with ECON off, so that is sort of valid.



Yikes, it looks like my speed dropped below 40 mph while I was climbing a hill on the freeway.

 

Great to see some accurate testing an analysis of the effects of the Eco button taking place.

It is important to note that in Simon's initial test of the Eco button where he found an increase of fuel economy from 48.0MPB to 52.6MPG, this is a total fuel savings of 0.182gallons/100miles, attributed to the use of the Eco button.

Applying this same level of fuel savings to someone getting 30MPG, would result in an increase to only 31.74MPG. So recognize that in interpreting these results, that you will not see the same level of MPG increase, the lower your fuel economy is.

 

I love people that geek out over this sort of thing. Thank you!

 

The Fit makes it really easy to geek out over. Some other cars just don't provide you with the feedback to help you drive more efficiently.

A few weeks ago my Fit had to get serviced at the dealer so I got a rental Hyundai Elantra for a few days. I told myself I would try and hypermile in it, but I just couldn't. There was no realtime MPG guage to tell me if certain behavior was helping or not. There was no green glow that I could see in my peripheral vision when I was driving efficiently. The geared automatic transmission couldn't smoothly adjust for optimum efficiency like my Fit's CVT can. I just gave up and drove like a normal person.

 

Thank you.


I have also developed an mild obsession with the mileage readout, although I'm happy to just do it from the computer. Without an iota of the detail in this report, it seems to me I get 3-5 mpg more per trip of any duration with the ECON button on.


More to the point for me, however, is that I like how smooth and refined the car feels with it on. I seem to always default back to D and ECON even though I've tried the other possible combinations in my EX.
Gutless, yes, but my trips are all stoplight to stoplight. I picked the car up two months ago, and today is the first day I was on an interstate with it...for 5 minutes.


Per the computer I'm at 31.2 mpg average over those two months. I still haven't reached the 600 mile break in point.

 

My god man. If I could give you money for preaching the truth.

 

Premature to really be checking back in, but I'm 3/4 through my first tank with ECON off. This was probably a terrible first tank to try for comparison as most of it was driven a completely different route than my norm. It was DragonCon weekend, and I've spent about half of the tank going to and from DragonCon for 3 days -- which included more downtown driving than I usually experience, and probably different hills and speed limits and such. So far I'm running about 3 MPG lower than I would typically be by about now, and while I would have sort of expected that without ECON, I should exclude this tank entirely from my longer term average and go with the overall MPG for the next 3-4 tanks.

 

Follow-up: I'm abandoning my long-term trial without the ECON button. While my conditions and driving habits were more varied over the earlier portion of my "with ECON" time, the last 5 fill-ups with ECON were all under the same conditions and driving habits. There was variation from tank to tank, but the lowest MPG was 36.9 and the highest was 39.5. Overall average over that time period (calculated using total miles and total gallons over that time period, not the average of the individual tank MPGs) was 37.6.

So my first full tank without ECON under the same conditions (route and such) was with the same driving habits -- no notable events regarding heavier or lighter traffic or unusual trips that were out of the ordinary. I ended up with 34.4 MPG. That's 2.5 MPG lower than the lowest in my "with ECON" sample and 3.2 MPG lower than the average. While there is still some remote possibility of conditions having varied more than I was able to notice, I really doubt it. I'm concluding that the more likely reality is that the ECON button does generally effectively improve the fuel economy under the same driving conditions and habits, and fairly significantly so. I generally would prefer a larger sample, but this isn't just at the low end of my typical range. Because I don't think it is likely that this is an aberration, continuing to do this for 4 more tanks seems to me like it is more apt to just cost me while continuing to provide more of the same results. I do understand that my result will not offer certainty on this.

Other observations: Driving without the ECON vs. with... Acceleration and throttle responsiveness are definitely more obvious without. As someone mentioned, the ECON "dulls the throttle". Using cruise control, the car keeps speed on hills without ECON whereas it loses a bit of speed with. Not a huge difference but noticeable as it was generally more aggressive in keeping speed without ECON. The air conditioning -- I can't honestly say that I noticed a massive difference. It did seem a bit colder and did seem to cool slightly quicker without ECON, but the apparent different is so slight that I can't say how much of this was actual and how much was merely due to my subjective judgment as conditioned by my expectations. I'd rather leave this one as "uncertain" than to say that there was a true difference. I didn't do any kind of testing with a thermometer on identically hot days. Here in Georgia we were in the high 90s outside and the inside of the car was hot as hell each time I got in (even with 35% tint and a windshield shade). Reminding me -- those "hypermilers" who drive around with the windows up and no air conditioning must live in cooler regions. I'm pretty sure we would suffer brain damage trying to drive around like that here. Windows must be down or AC must be on.

At least one person reported slightly better MPG with ECON off -- I would wonder how much confidence there was in same conditions/habits as "on". And if that result is real, it would bring up the question whether there are some set of driving conditions that are actually worse for the ECON mode, and if so, what are they?

That's it. If anyone else wants to take up a longer term comparison I'll defer to those tests. I don't want another 34 MPG tank if I can avoid it.

 

Chris,

Thanks so much for your econ testing results. If I am doing the math correct, ECON improves your efficiency by 11%, right? That's the exact same percentage I got in my test in the first post of this thread. The agreement of our results is encouraging that our tests are useful.

I am one of those crazy hypermilers that drives with the windows closed and AC off. I live in Washington, D.C which has summers in the 90s. Sometimes I am forced to turn on the AC if I start to sweat but I manage to keep it off 95% of the time, unless I am riding with passengers. Here is my technique:

If it isn't too hot, I can just run the blower fan and intake fresh air.
If it is too hot, it gets complicated.

• open windows at stop lights to get a breeze
• open windows as an "air brake" to slow the car if I am coasting to a red light. I can feel the car slow faster when I do this, especially at high speed, for example when taking an off ramp from the highway I can do this to slow down for the exit, while also reducing brake pad wear
• in direct sunlight, sometimes open windows for 10 seconds just to flush out the interior which is green-housing itself with the all black interior that can not be overcome by simply intaking cooler, fresh air with the blower fan
• at speeds below 40mph, air drag is minimal, so I might drive with the windows open for the first five minutes until I get on the highway
• Parking in the shade can eliminate being forced to run the AC to cool a car that has been baking in the sun for hours
• I can cool my body without AC, by stripping to my undershirt or drinking an icy beverage. This part definitely makes others think I am crazy.

 

After driving with the econ button on for three full tanks I had mpgs of 40, 39, and 38. My first tank (so far) with the econ button off I've gotten 40 mpg and had slightly more fun doing it. My very informal tests are so far showing that the econ button should be relabeled to the "suck" button. This is of course taking into account that I'm barely more than halfway through this test of mine.

 

As you are reporting on a partial tank, I'm wondering if you're possibly utilizing the inaccurate fuel economy reporting done by the car itself rather than calculating it externally using gallons of fuel used and total miles driven?

I failed to clearly mention that my results were computed on full tanks using the gallons consumed and miles driven, with no use of the car's MPG tracking.

That said, I speculated on whether there could be circumstances which would lead to no significant difference between using ECON and not using it (which could definitely be), but at least for my driving conditions and some others the ECON button does appear to have a very real and significant effect which I wouldn't describe as a "suck button". Were you to discover that those circumstances are true for you, I would agree that it would be foolish to bother with the ECON button. I'd love to have more data on this -- but it seems that the majority of others are pretty well convinced that the button does actually have a positive impact on fuel economy for their circumstances and are unwilling to try for long-term comparisons as I set out to do before having my fuel economy plummet after turning it off. Anyone taking measurements would need to do the calculations properly and disregard the trip computer.

 

Thanks for the data. The econ button does make the car "suck", but we are wondering if the fuel savings are worth the reduction in acceleration. It definitely saves a little fuel but maybe not enough for people to have less fun driving or not-as-cold air conditioning.

Question. How often are you running the AC? The econ button should have more significant fuel savings with the AC on, because the econ button cycles the compressor on and off to reduce load, but the air gets a tad bit warmer when the compressor is off.

If we eliminate AC from these tests, then maybe the ECON button is mainly helping the driver accelerate more slowly. But if the driver is already skilled at accelerating slowly, the ECON button maybe have little effect.

The driver's technique and skill have the largest impact on fuel economy than any other eco-modication. Since we all have different driving styles, the effectiveness of the ECON button may vary quite a bit.

 

Simon, great questions and great points. I have a couple of thoughts on this (but would love to hear more from the other fellow). I guess I mentioned already that in my case I'm driving around with the AC on nearly all the time -- excepting the morning when I throw open the moonroof, or the occasional late evening (i.e., 9 PM or so when it's cool) with the moonroof.

As far as other factors, I personally am very conscious of my acceleration whether the button is off or on, but because I tend to flip on the cruise control after reaching speed (I don't let it accelerate for me) when I'm not driving around town and subject to constant traffic and stop lights, the car is doing its thing and probably eats up more fuel without ECON on these hilly back roads with the aggressive (not "dulled") throttling. But I would wager that for anyone who considers the ECON button to have made the car significantly "less fun to drive", those would probably not be the ones who are either "skilled at accelerating slowly" or at least who aren't inclined to do so, and I'd actually expect the ECON mode to improve their results. Unless, that is, they're accelerating somewhat briskly but still not outright aggressively without it and liking that pace, but then going really hard at it with the ECON button on to overcome the dulled throttle and perhaps overdoing it. I'm speculating a whole lot, but without data, that's where we are.

The other fellow (I'm too lazy to scroll back and catch his name -- sorry) is getting pretty decent results (apparently better than me! -- though question remains whether he's using the trip computer or calculating offline) even though he mentions that he enjoys the acceleration without the button. I'd think that he's either not driving around town with a lot of stop-and-go situations, or has decently level roads (not hilly) or both -- because I'm not attaining what he's reporting and I'm not terribly far from driving at least somewhat like a hypermiler. I'm pretty slow at acceleration, try to manage stops very actively (avoiding braking as much as possible), etc. -- but I do have a hellaciously hilly terrain with some really long hills (nearly a mile sometimes) alternating with the roller coaster like rolling hills. Then I'm in town type terrain about half the time -- stop lights every 10 feet, traffic, people pulling in front of me suddenly. I'll never average 40MPG even if I dispense with the AC and get even more grandma-like with my driving.

The data I would love to have will probably never be available. I think you're on the right track to wonder how it works out with and without the A/C for both ECON ON and OFF -- all under roughly similar circumstances. That would be 4 sets of measurements each over time for each person. That would tease out how well the button works at all for a variety of people and how much of it (where it does help) is due to A/C moderation vs. throttle moderation.

 

Don't have an Eco choice