Mileage w/ECO Mode (Houston-Ft Stockton)

Not sure what to make of these numbers, but I thought I'd post them to add to the discussion about using or not using ECO mode.

Back in January, we drove from Phoenix AZ to Cocoa Beach FL and got the following mileage between Ft Stockton and Houston. I did not use ECO mode on this trip.
Ft Stockton to Selma 34.8 mpg @ 68 mph
Selma to Houston 39.3 mpg @ 67 mph
Avg 36.3 mpg

Just last week, we drove from Richmond Hill GA to Phoenix AZ and got the following mileage between Houston and Ft Stockton. I decided to try using ECO mode for this trip.
Houston to San Antonio 46.1 mpg @ 70 mph
San Antonio to Ft Stockton 39.5 mpg @ 77 mph
Avg 41.8 mpg

Note: San Antonio and Selma are essentially the same, just different service stations along Hwy 1604. Cruise control set at 2-3 mph over the limit was used wherever possible.

I realize these trips were in opposite directions and at different times of the year, so I'm not sure how much the wind/cold in January may have affected the first set of numbers. However, I'm encouraged that even running up to 9 mph faster, I was able to get 5.5 mpg more using ECO mode. We will be making the trip back to Richmond Hill GA next month and I'm going to try to duplicate most of the 2nd trip to see what numbers I get then. I'm already semi-convinced that using ECO mode results in 3-5 mpg more, but I have to say that there were times in traffic when ECO mode left a lot to be desired, though I muscled through without switching it off. I don't have a regular commute, so it's very difficult to make many comparisons and draw conclusions, so I'm left with subjective opinions.

 

Sorry, I know what ECO mode does and didn't say it alone increases mileage. However, saying it has little affect on mileage is misleading IMHO. While it doesn't directly affect mileage, it helps many drivers accelerate more slowly because of the reduced accelerator sensitivity without having to think about doing so or watch the display, etc. I found it particularly helpful in heavy traffic to keep from constantly accelerating/braking. The reduced sensitivity kept me from accelerating only to hit the brakes and the drive through Houston and San Antonio traffic was more relaxed during this trip. Obviously, if one presses the accelerator that much harder, turns the A/C fan speed higher, etc., it negates the effects of ECO mode and is basically useless. However, since I'm not in a hurry, use cruise control on the highway, etc., it seems to have helped me increase my mileage and that's my only point. Use it or don't use it, makes no difference to me. I intend to use it on our trip next month to get some more data to analyze and then decide what to do in the future.

 

I can appreciate that. I didn't like it when I experimented with it when we first bought the car last year, it was enough just to get used to the reduced power of the Prius. But now that I'm used to that, I no longer find ECO mode all that bad. Different strokes I guess and I still might go back to not using it.

 

And that first part is the key point. If you are already adept at getting good numbers, ECO mode probably won't do much, if anything, for you. I just drive the car, so ECO seems to have helped me get better numbers and that's my only point.

I was surprised to find that gas prices here were some of the more expensive on the trip at $2.699/gal. I know that's cheap compared to yours and I understand that we switched over to the more expensive summer blend, but it's still frustrating to see prices fluctuate the way they do and see them vary so much across the country.

 

Unfortunately, no regular commute, so empirical data just isn't in my future. When I tested ECO mode the first time, my experience was basically the same as yours. But now that I've gotten used to the Prius, I'm not having the same experience. I have actually grown to like the reduced response of the Prius in general and don't much care for driving my truck or faster cars these days. I find the slower pace of the Prius to be more relaxing and it just fits my current driving style, especially on trips. ECO mode isn't that comfortable in stop and go traffic though, so I do turn it off at times.

 

I've often wondered about the tire pressure at highway speeds. After we get to Georgia on our next trip, I might reduce mine to what's on the door and see if/how it affects mileage on the way back home. Like this post, the test won't be scientific, but it may still tell me something.