ECO mode - What does it actually do?

[Kenneve]

Have been running around for several weeks now in mainly ECO mode, but not really certain what effect it has.
As far as I can see, it takes the edge off peak acceleration and reduces the efficiency of the heater system, for a very minor improvement in fuel consumption, maybe 3 or 4%.
Can anyone confirm these findings or am I missing something?

[John Ratsey]

The primary function of Eco mode is to widen the allowable gap between target and actual cabin temperatures. This is more noticeable in cold weather as it reduces the amount of time the engine is running only to keep the cabin warm. I think Eco also reduces the aircon performance which may be noticeable in very hot weather.

I can't comment on whether Eco adversely impacts acceleration as I've always had Eco enabled and find the acceleration more than adequate. However, sensibly it will encourage the engine to keep out of the least efficient part of its operating range.

[Mellorshark]

the engine is running only to keep the cabin warm.

Isn't it also charging the battery?

[Kremmen]

On all 3 of my previous Civics Eco mode was a disaster. It noticeably dulled the throttle and in the Summer on hot days it almost completely turned the Aircon off.

I've not owned the Jazz through Summer yet but the throttle response doesn't seem to be anywhere near as severe.

On the Civics, trying to accelerate sufficiently along a motorway slip road to blend in was almost impossible. So far, the Jazz acceleration seems unaffected by Eco and motorway blending seems the same whether it's on or off for me

[Jeff15]

I don't use the Eco mode, for me it seems to make no difference to fuel economy which I would have thought was the whole point of it..

[Kremmen]

But you get a pretty green leaf in the dash 

[John Ratsey]

the engine is running only to keep the cabin warm.

Isn't it also charging the battery?

Under normal operation the engine will cut out once the battery gauge reaches 7 bars so there's capacity to accommodate regenerative braking. If the engine is still running to provide heat then the load will be minimal and the efficiency drops significantly.

[peteo48]

I have started using the Econ button (alongside B mode) for most of my trips which are predominantly short urban journeys. At this level I don't notice any reduction in acceleration but I drive with a light right foot anyway. I can't detect any reduction of heating or aircon - I'm sure there is some but I don't notice it.

On longer trips, certainly using the very busy motorways round here, I'll tend not to use Econ or B for that matter.

[Jeff15]

But you get a pretty green leaf in the dash 

Yes, I forgot to mention that, it's very pretty......

[Pine]

On my last car (Toyota) I wouldn't use Eco Mode because it dulled the performance so much and struggled uphill.  But at the last fill-up I decided to try it on my Jazz.  To my surprise I am finding the performance perfectly adequate and the MPG is definitely improved.  It has been a hot week but the aircon still keeps the interior at a comfortable temperature. One thing I have noticed is that when the engine fires up I am sure it is running at reduced revs when compared to Normal Mode. 

[Nicksey]

Similarly to Pine, my last 3 Renaults all had ECO mode, and with all 3 I never used it. It just dulled everything, with no noticeable benefits. There was the chance to increase a nice little glowing line of 'cabbages' on the display.. but that was it. Therefore, the least worn part of my Jazz I can safely say is the ECO button. Never used it, never will.

[Downsizer]

I switched eco on when I bought the car 11,000 miles ago and have no complaints, even with the temperatures in the mid 30’s, so I’ll stick with it.