I've been tracking my mileage fairly religiously over the past 9 months or so. I bought the van new last March, and have always driven with Eco mode on. I've seen many comments basically stating "Turn it off, it does nothing". So as an experiment, after my last fill up I turned it off. Today I filled up again, plugged my numbers in, and the result is that I have had the worst mileage since I've been keeping track: 14.1L/100km (16.7mpg) Most of my driving is city. After today's fill up, I turned the Eco mode back on, so we'll see what kind of numbers I get with this tank.

 

Articles on the subject say ECO mode boosts mileage 1 to 2 MPGs. Hope you prove them wrong.

 

Well, right now my preliminary results based on past mileage is proving them very right. We'll see what happens over the next couple of weeks.

 

OK, filled up today and it looks like the ECO boost improves my gas mileage by 1.14mpg. With ECO off, I got 14.1 L/100km (16.68mpg), and with it on I got 13.2 L/100km (17.82mpg). It's a pretty accurate figure. Both tanks of gas were emptied the same way, strictly city driving around town. Not sure if there would be any noticeable difference between ECO/non-ECO on the highway, as once the transmission gets into 6th gear, I think both modes operate the same.

 

I've got about 1 L / 100 km city too. So ECO really work.

 

I don't use the Eco, but I have been getting 22 mpg within the city.

 

I don't know what kind of "city" driving you're doing to get 22, but I average a hair over 18 in the city. That's literally 0 freeway driving. We did manage 28.4 for one tank only, between Sacramento and Long Beach. That's my current best tank. I don't use eco because I find it to be a bit less smooth. I drive gently anyway, so I figure that's the only difference that eco mode is making really. Id like to see the difference if someone scientifically goes through it though.

 

very interesting discussion here. We just purchased a 2012 GC last week. Drove it home from out of state approx. 90miles, then city driving every since. We tried the ECO mode but like, AdamJohn said, it was noticeably less smooth so we turned it off. The lcd indicator showed an average of 21.5mpg for this first tank without using ECO mode. Not bad at all as far as I'm concerned!

Its also important to note that this year model and I believe the 2011s as well have a Transmission Control Module recall in place. We are having ours done next week. This is said to correct the ECO mode issues as well as the rough transmission engagements. We see it when backing up or doing 3 point turns.

good post