Eco mode and bad gas mileage

All I can think: you need to really tromp the pedal to get a reaction, maybe easier to modulate in normal mode?

 

ECO mode hates you.

 

We used ECO for maybe the first eight months of ownership. I started tracking mpg about one month in. After switching to normal I noticed no appreciable change.

I'd just switch it off, cut your losses.

 

Yes, this has happened to other people, though not me.

The ECO/Normal/PWR setting is mostly a user interface thing, not a change to the actual propulsion system. Use whatever mode works best for you.

For a person with superhuman dexterity and response speed and patience, there should be no difference. Among ordinary humans, a majority (or is is a just a plurality?) of us do best in ECO, but a significant number of others do best in either Normal or PWR. And some actually do find no difference, though we don't yet know if they qualify as 'superhuman'.

There are some minor tweaks to other systems (AC, cruise control, temperature thresholds) that should produce slightly better mpg in ECO mode in certain operating conditions, but have no impact in many other conditions.

 

But did you drive the same routes under similar conditions or are you just comparing general routes that you think are similar? I've now got almost 35,000 miles on our 2014, most of it at highway spends using cruise control, and I still can't tell if there is a difference or not. When I first tested ECO mode on a cross-country trip, it appeared that my mileage was better. However, I've made that trip a number of times now and I've gotten both better and worse mileage. Unfortunately, I didn't take the time to fill up at exactly the same places along the route for a more definitive comparison and filling up, for example, before Albuquerque going west is a lot different than filling up in Albuquerque. And the weather as well as traffic patterns were different on each trip. You can drive across New Mexico and Texas on I-10 or I-40 one month and not hit any headwinds. Try another month and you fight winds all the way. Temps in January are a lot different that in July. Traffic patterns, especially 18-wheelers, also vary greatly from day to day and even at different times of the day. I look at the average mileage for each trip and overall and see very little difference, certainly nothing substantive. And this last trip I actually issued PWR mode quite a bit for the first time in Houston and Atlanta and felt my mileage was better than it would have been in Normal or ECO mode. I caulked this up to getting up to speed quicker so I could cruise longer. And it was just an impression, but sure made driving in those cities a lot more enjoyable, though enjoyable is not the right word for such traffic.

 

it's more about how you drive than anything else. unless you do somewhat controlled testing, you really can't compare.

 

For the Gen III Prius, one's overall driving style is more important than what driving mode they are in. Just like any other car, anticipating traffic ahead and safely avoiding sudden stops saves gas. I personally use "normal" mode and am happy with my mileage.

 

ECO is a accelerator pedal to throttle map, it will have no effect when you are not using the pedal. (Cruise Control will be the same in all modes) Unless the difference in A/C affects your MPG, the modes will not change CC driving.

 

Sounds silly, but differences in seating position and even shoes worn make a difference in how you can modulate the pedal. When I wear shoe boots in the winter, the thicker soles and heavier weight force me to move the seat back a bit. Some positions/shoes make it too easy to press harder.

But I have noticed the same mileage in normal, and a much happier experience overall than ECO mode.

 

How many miles are we talking here? Are you going by the CONS display?

 

also be sure to keep everything else constant! (AC/gas/tire inflation etc)
a trip which usually gave 50mpg on shell gave me 35mpg on CITGO gas,
and when i emptied the tank and refueled with shell it went back up to 50.
and this is with regular gas too

 

Another good reason to maximize driving on cruise control.

In my case, I use the "pat UP" and "pat DOWN" to make +1 and -1 mph changes. In effect, I trim the cruise control for current conditions including dealing with steep hills. I'm also OK with shifting into "N" in some cases to avoid cruise control induced charging and using "B" on 500 ft. hill descents.

In effect, I drive my Prius using cruise control as an automatic speed mechanism that I trim as needed and the shifter as an automatic, manual transmission.

My only complaint about cruise control is it should go down to below the maximum range speed, ~17-18 mph. Say, 15 mph would work for me. I would also like "ECO"+cruise control to allow a +/- 3 mph slop to slack off when engine rpm > 3,200 rpm and slop a little faster when no energy is required versus forcing a charge.

Bob Wilson

 

I was always a cruise control guy before I bought the v Bob. Back and forth on my interstate drive, I hardly use it anymore because of the drop in mpg. As it maintains speed uphill, I watch as it ruins my mileage. I've also used it normally, and just canceled it when going up hills. But overall, I find I can easily get better mileage without cc on. Probably not an issue if you live in relatively flat terrain.

 

Agreed Bob, but not all cruise controls are created equal, nor engines. My Avalon, Camry's, and the Corolla would be fine on cruise control wherever. Mileage almost always the same. The Prius does not have the oompha nor the intelligence to maintain efficiency using cc. One of the features I most dislike about the car. On my next tank, coming right up, I'll try to use the cc as much as possible to see what the hit really is for an entire tank.

 

The OP say's they are "playing" with all the modes or experimenting with them.
It's a 2015 Prius 2.

So I think this is another situation where we have a new owner over reacting to immediate feedback.
And I don't mean to sound adversarial.

But it sounds like the OP hasn't even owned the vehicle very long.

My advice? I drive in either ECO or Normal....I would choose one of those modes. Normal is good.
Then just drive. I suspect there is absolutely nothing wrong here. Figure out your average MPG when you fill the tank. And try NOT to experiment with all the modes. Except maybe on a tank to tank basis.

What Toyota doesn't really tell you, what any automaker doesn't really tell you, is that your EPA estimated MPG is just that, and estimate taken from a specific test. The Prius as a hybrid is a remarkable machine in comparison to many vehicles on the road. But it still runs an engine, that runs on gasoline. And that engine is still vulnerable to many of the factors that affect any gasoline engine. Outside temperature, driving conditions, driving style, tire inflation, etc, etc...

See what your average MPG are over a course of a month, or even months. The Prius responds well on many levels to "The Middle Way". Efficiency numbers will drop with the extreme heat of summer and the extreme cold of winter.

But assuming your vehicle is operating correctly, and you don't have something as obvious as overfilled oil or under inflated tires, my guess is that you aren't really getting bad or horrible gas mileage in ECO mode.

Even as a multiple year owner of a Gen 3 Prius I have found that sometimes the reported MPG on a trip to trip basis can be puzzling. Trips that I think should reflect good efficiency are sometimes reported disappointingly, and other trips, where I think I have been a heavy footed, gas demanding fool, come back with better numbers. It's a learning curve. BUT part of that learning curve I think, is to really look at your MPG's on a tank to tank, month by month basis.